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Abstract:

The present invention relates to urea-terminated polyurethanes
dispersants based on diols and polyether diols, aqueous dispersions of
such polyurethanes, the manufacture of the urea terminated polyurethane
dispersions and inks containing pigments and/or disperse dyes dispersed
with these urea terminated polyurethane dispersants. The urea termination
can have nonionic hydrophilic substituents.

Claims:

1. An aqueous colorant dispersion comprising a colorant and a urea
terminated polyurethane ionic dispersant in an aqueous vehicle, wherein:
(a) the ionic dispersant is physically adsorbed to the particle, (b) the
polymeric ionic dispersant stably disperses the pigment in the aqueous
vehicle, (c) the average particle size of the dispersion is less than
about 300 nm, wherein the urea terminated polyurethane dispersant
comprises at least one compound of the general structure (I):
##STR00006## R1=alkyl, substituted alkyl, substituted alkyl/aryl
from a diisocyanate, R2=alkyl, substituted/branched alkyl from a
diol, R3=alkyl, branched alkyl, or a isocyanate reactive group from
an amine terminating group, R4=hydrogen, alkyl, branched alkyl, or a
isocyanate reactive group from the amine terminating group; where the
isocyanate reactive group is selected from hydroxyl, carboxyl, mercapto,
or amido; n=2 to 30; and where R2=Z1 or Z2 and at least
one Z1 and at least one Z2 must be present in the polyurethane
composition; ##STR00007## p greater than or equal to 1, when p=1, m
greater than or equal to 3 to about 30, when p=2 or greater, m greater
than or equal to 3 to about 12; R5, R6=hydrogen, alkyl,
substituted alkyl, aryl; where the R5 is the same or different with
each R5 and R6 substituted methylene group where R5 and
R5 or R6 can be joined to form a cyclic structure; Z2 is a
diol substituted with an ionic group; wherein the urea content of the
urea-terminated polyurethane is at least 2 wt % of the polyurethane and
at most about 14 wt % of the polyurethane, and the colorant is selected
from pigments and disperse dyes or combinations of pigments and disperse
dyes.

2. The aqueous colorant dispersion of claim 1 where the where urea
content of the urea terminated polyurethane is at least about 2.5 wt %
and at most about 10.5 wt %.

3. The aqueous colorant dispersion of claim 1 where the polyurethane
dispersant has structure (I), with p=2 or greater and m is greater than
or equal to 3 to about 12.

4. The aqueous colorant dispersion of claim 1 where the polyurethane
dispersant has an ionic content of about 10 to 210 milliequivalents per
100 g of polyurethane.

5. The aqueous colorant dispersion of claim 1 where the polyurethane of
dispersant comprises a polyether diol Z2 m=3 and the ether is group
is derived from biochemical transformations.

6. The aqueous colorant dispersion of claim 3 where the polyurethane
dispersant comprises a polyether diol Z2 which is at least 50 weight
percent of the polyether diol.

7. The aqueous colorant dispersion of claim 3 where the polyurethane
dispersant comprises a polyether diol Z2 which has a number average
molecular weight of 200 to 5000.

8. The aqueous colorant dispersion of claim 3 where the polyurethane
dispersant comprises a polyether diol Z2 which has m=3 or 4.

9. The aqueous colorant dispersion of claim 3 where R5 and R6
of the polyurethane dispersant are hydrogen.

10. The aqueous colorant dispersion of claim 3 where Groups R3 and
R4 of the polyurethane dispersant are substituted with nonionic
hydrophilic groups.

11. The aqueous colorant dispersion of claim 3 where Groups R3 and
R4 of the polyurethane dispersant are methoxyethyl.

12. The aqueous colorant dispersion of claim 3 where Groups R3 and
R4 of the polyurethane dispersant are alkyl.

13. The aqueous particle dispersion of claim 1 where the colorant to urea
terminated polyurethane dispersant ratio is from about 0.5 to about 6 on
a weight basis.

14. An aqueous colored ink jet ink comprising the aqueous colorant
dispersion of claim 1, having from about 0.1 to about 10 wt % pigment
based on the total weight of the ink, a weight ratio of colorant to urea
terminated polyurethane dispersant of from about 0.5 to about 6, a
surface tension in the range of about 20 dyne/cm to about 70 dyne/cm at
25.degree. C., and a viscosity of lower than about 30 cP at 25.degree. C.

15. An inkjet ink composition comprising an aqueous vehicle and colorant
particles stabilized by an urea terminated polyurethane dispersant in an
aqueous vehicle wherein: the urea terminated polyurethane dispersant
comprises at least one compound of the general structure (I):
##STR00008## R1=alkyl, substituted alkyl, substituted alkyl/aryl
from a diisocyanate, R2=alkyl, substituted/branched alkyl from a
diol, R3=ahydrogen; alkyl; a non-isocyanate reactive substituted,
isocyanate reactive substituted, or branched alkyl from the amine
terminating group; R4=hydrogen; alkyl; a non-isocyanate reactive
substituted, isocyanate reactive substituted, or branched alkyl from the
amine terminating group; where the isocyanate reactive group is selected
from hydroxyl, carboxyl, mercapto, or amido; n=2 to 30; and where
R2=Z1 or Z2 and at least one Z1 and at least one
Z2 must be present in the polyurethane composition; ##STR00009## p
greater than or equal to 1, when p=1, m greater than or equal to 3 to
about 30, when p=2 or greater, m greater than or equal to 3 to about 12;
R5, R6=hydrogen, alkyl, substituted alkyl, aryl; where the
R5 is the same or different with each R5 and R6
substituted methylene group where R5 and R5 or R6 can be
joined to form a cyclic structure; Z2 is a diol substituted with an
ionic group; wherein the urea content the urea-terminated polyurethane is
at least 2 wt % and at most about 14 wt % of the polyurethane, and the
colorant is selected from pigments and disperse dyes or combinations of
pigments and disperse dyes.

16. The inkjet ink of claim 15 where the polyurethane dispersant has
structure (I) p=2 or greater and m is greater than or equal to 3 to about
12.

17. A process for making a dispersed pigment comprising the step of
mixing the pigment and a urea terminated polyurethane dispersant in an
aqueous carrier medium, then dispersing or deflocculating the pigment.

18. The method of claim 17, wherein the dispersing is accomplished in a
process selected from the group consisting of 2-roll milling, media
milling, and by passing the mixture through a plurality of nozzles within
a liquid jet interaction chamber at a liquid pressure of at least 5,000
psi.

19. A process for making a dispersed pigment comprising the steps of a)
preparing a urea terminated polyurethane dispersant and then mixing the
pigment and the urea terminated polyurethane dispersant in an aqueous
carrier medium, then dispersing or deflocculating the pigment where the
urea terminated polyurethane (Structure I) is prepared by (a) providing
reactants comprising (i) at least one diol Z1 ii) at least one
polyisocyanate component comprising a diisocyanate, and (iii) at least
one hydrophilic reactant comprising at least one isocyanate reactive
ingredient containing an ionic group, Z2; (b) contacting (i), (ii)
and (iii) in the presence of a water-miscible organic solvent to form an
isocyanate-functional polyurethane prepolymer; (c) adding water to form
an aqueous dispersion; and (d) prior to, concurrently with or subsequent
to step (c), chain-terminating the isocyanate-functional prepolymer with
a primary or secondary amine.

Description:

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority from U.S. Provisional Application
Ser. No. 61/005,977 (filed Dec. 10, 2007), the disclosure of which is
incorporated by reference herein for all purposes as if fully set forth.

FIELD OF THE INVENTION

[0002] The present invention relates to urea-terminated polyurethanes
dispersants based on diols and polyether diols used singly or in
combination. These polyurethanes dispersants are effective for dispersion
of particles, especially pigment particles. Pigments dispersed with the
polyurethane dispersants can be used in ink jet inks.

BACKGROUND OF THE INVENTION

[0003] Disclosed herein are novel, stable aqueous particle dispersions.
The polyurethane dispersants that produce the stable aqueous particle
dispersions, especially pigment dispersions, the process of making the
pigment dispersions, and the use thereof in ink jet inks are also
disclosed herein.

[0004] Polyurethanes are materials with a substantial range of physical
and chemical properties, and are widely used in a variety of applications
such as coatings, adhesives, fibers, foams and elastomers. For many of
these applications the polyurethanes are used as organic solvent-based
solutions. However, recently environmental concerns have caused
solvent-based polyurethanes to be replaced by aqueous dispersions of
polyurethanes in many applications.

[0005] Polyurethane polymers are, for the purposes of the present
invention, polymers wherein the polymer backbone contains urethane
linkage derived from the reaction of an isocyanate group (from, e.g., a
di- or higher-functional monomeric, oligomeric and/or polymeric
polyisocyanate) with a hydroxyl group (from, e.g., a di- or
higher-functional monomeric, oligomeric and/or polymeric polyol). Such
polymers may, in addition to the urethane linkage, also contain other
isocyanate-derived linkages such as urea, as well as other types of
linkages present in the polyisocyanate components and/or polyol
components (such as, for example, ester and ether linkage).

[0006] Polyurethane polymers can be manufactured by a variety of
well-known methods, but are often prepared by first making an
isocyanate-terminated "prepolymer" from polyols, polyisocyanates and
other optional compounds, then chain-extending and/or chain-terminating
this prepolymer to obtain a polymer possessing an appropriate molecular
weight and other properties for a desired end use. Tri- and
higher-functional starting components can be utilized to impart some
level of branching and/or crosslinking to the polymer structure (as
opposed to simple chain extension).

[0007] Polyurethanes have been prepared from diols as disclosed in
Statutory Invention Registration US H2113 H but with the limitation that
the polyurethane has a hydroxyl number greater than 10 and thus the
polyurethanes described are not urea terminated. Polyurethane have been
prepared from polyether diols as disclosed in EP1167466, US2004/0092622
and US2003/0184629 but these polyurethanes are chain extended with di or
triamines, which will result in a polyurethane which has been bridged by
the di or triamine chain extension. US2004/0229976 describes the use of
polyurethane resins as freely added materials in pigment-dispersed
aqueous recording liquid which have at most 2.0 wt % of polyurethane urea
in the polyurethane.

[0008] Polyurethanes with both monofunctional end-capping and chain
extension of the polyurethane have been described in WO2006/027544.

[0009] Polyurethanes have also been prepared using polytrimethylene ether
glycol (PO3G) based homo and copolymers, as disclosed in U.S. Pat. No.
6,852,823, U.S. Pat. No. 6,946,539, US2005/0176921A1, U.S. application
Ser. No. 11/294,850 (filed Dec. 6, 2005), and Conjeevaram et al. (J Polym
Sci, 23, 429, (1985)), the disclosures of which are incorporated by
reference herein for all purposes as if fully set forth. The most common
source of PO3G and its precursors are from biosynthetic pathways that are
described in the aforementioned patents and applications. Polyurethanes
derived at least in part from biosynthetic pathways are important
nowadays, as they reduce our reliance on the petrochemical industry.

[0010] Aqueous dispersions of self-dispersing, ionic polyurethanes have
also been proposed, for example, in U.S. Pat. No. 3,412,054 and U.S. Pat.
No. 3,479,310, the disclosures of which are incorporated by reference
herein for all purposes as if fully set forth. In these disclosures,
ionic and/or non-ionic or potentially ionic diols are incorporated into
the polyurethane polymer and, following neutralization, these
polyurethane ionomers can be stably dispersed in water.

[0011] Typically, polyurethane dispersions have been made using a wide
range of polymeric and low molecular weight diols, diisocyanates and
hydrophilic species. The dispersion process may involve synthesis and
inversion from volatile solvent such as acetone, followed by distillation
to remove organic solvent components. Polyurethanes may also be
synthesized in the melt phase with or without inert, non-volatile
solvents such as NMP (N-methylpyrrolidone). In this case, the solvent
remains in the polyurethane dispersion. Added emulsifiers/surfactants may
also be beneficial to dispersion stability.

[0012] Recently, polyurethane dispersions have been extended to
acrylic/polyurethane hybrids and alloys, such as disclosed in U.S. Pat.
No. 5,173,526, U.S. Pat. No. 4,644,030, U.S. Pat. No. 5,488,383 and U.S.
Pat. No. 5,569,705, the disclosures of which are incorporated by
reference herein for all purposes as if fully set forth. This process
typically involves synthesis of polyurethanes in the presence of vinylic
monomers (acrylates and/or styrene) as the solvent. Following inversion
to form a polyurethane dispersion, the acrylic or styrenic monomers are
polymerized by addition of free radical initiator(s). Variations on this
process are known in the art. Acrylic/urethane hybrid dispersions offer
potential advantages to coatings and other end products, including
enhanced hardness, adhesion and nearly Newtonian rheology along with
lower cost, low VOC and improved manufacturing.

[0013] Polyurethane dispersions that are used as pigment dispersants have
been described in U.S. Pat. No. 6,133,890. These polyurethanes are
prepared with an excess of isocyanate reactive group and are limited to
the presence of polyalkylene oxide components. Aqueous polyurethane
dispersants have found limited use as dispersants for pigments and the
like.

[0014] Therefore, there is still a need for a new class of polyurethane
dispersants that can stably disperse particles, especially pigment
particles, in aqueous medium, and are especially suited for use in
aqueous inkjet inks. It would also be advantageous for such class of
polyurethane dispersants to be capable of being derived from
environmentally favorable ("green carbon") materials and of being
formulated into dispersion in a convenient environmentally friendly
manner.

[0015] None of the above publications disclose polyurethane dispersants
derived from water dispersible urea terminated polyurethanes based on
certain diols and polyether polyols which have at least 3 but less than
30 (substituted) methylene groups in the diol. It has been discovered
herein that these novel polyurethanes dispersants can be used as a
dispersants for pigments, especially pigments for inkjet inks, and have
the forgoing unique combination of attributes.

SUMMARY OF THE INVENTION

[0016] The use of polymeric conventional dispersants is well established
as a means to make stable dispersions of particles, especially pigment
particles. In general, these conventional dispersants have, at least,
modest water solubility and this water solubility is used as a guide to
predicting dispersion stability. These dispersants are most often based
on acrylate/acrylic compounds. During diligent searching for new,
improved polymeric dispersants, a new class of dispersants has been found
that are based on urea terminated polyurethanes, where the predominant
isocyanate reactive group is a hydroxyl which is part of certain diol
and/or certain polyether diols. The ionic content in these dispersants
can come from isocyanate or isocyanate-reactive components that have
ionic substitution.

[0017] In accordance with the invention, a new class of urea terminated
polyurethane dispersants has been found that produce stable aqueous
dispersions. When these dispersions are utilized for ink jet inks, images
printed with the ink display both improved optical density and
durability.

[0018] Accordingly, there are provided herein dispersants, namely urea
terminated polyurethane dispersants, that lead to stable aqueous
dispersions, stable aqueous dispersions containing these polyurethane
dispersants, methods of making urea terminated polyurethane dispersants,
inks based on urea terminated polyurethane dispersants, inks sets
comprising at least one ink based on an urea terminated polyurethane
dispersants, and methods of ink jet printing that use the inks based on
urea terminated polyurethane dispersants.

[0019] An aqueous particle dispersion comprising a particle and an urea
terminated polyurethane ionic dispersant in an aqueous vehicle, wherein:

[0020] (a) the ionic dispersant is physically adsorbed to the particle,

[0022] (c) the average particle size of the dispersion is less than about
300 nm,

where the urea terminated polyurethane dispersant comprises at least one
compound of the general structure (I):

##STR00001## [0023] R1=alkyl, substituted alkyl, substituted
alkyl/aryl from a diisocyanate, [0024] R2=alkyl,
substituted/branched alkyl from a diol, [0025] R3=ahydrogen; alkyl;
a non-isocyanate reactive substituted, isocyanate reactive substituted,
or branched alkyl from the amine terminating group; [0026]
R4=hydrogen; alkyl; a non-isocyanate reactive substituted,
isocyanate reactive substituted, or branched alkyl from the amine
terminating group; [0027] where the isocyanate reactive group is selected
from hydroxyl, carboxyl, mercapto, or amido; [0028] n=2 to 30; [0029] and
where R2=Z1 or Z2 and at least one Z1 and at least
one Z2 must be present in the polyurethane composition:

[0029] ##STR00002## [0030] p greater than or equal to 1, [0031] when
p=1, m greater than or equal to 3 to about 30, [0032] when p=2 or
greater, m greater than or equal to 3 to about 12; [0033] R5,
R6=hydrogen, alkyl, substituted alkyl, aryl; where the R5 is
the same or different with each R5 and R6 substituted methylene
group where R5 and R5 or R6 can be joined to form a cyclic
structure; [0034] Z2 is a diol substituted with an ionic group;

[0035] wherein the urea content of the urea-terminated polyurethane of
general structure (I) is at least 2 wt % of the polyurethane and at most
about 14 wt % of the polyurethane,

[0036] and the colorant is selected from pigments and disperse dyes or
combinations of pigments and disperse dyes.

[0037] Structure I denotes the urea terminating component and Structure II
denotes the diol and/or a polyether diol that is a building block for
Structure I.

[0038] In one aspect of the present invention, there is provided a
pigmented ink comprising an aqueous carrier medium and particles of
pigment stabilized by a polyurethane dispersant comprising a
urea-terminated polyurethane, where the urea-terminated polyurethane
dispersant comprises at least one compound of the general structure (I).

[0040] The present invention further provides an aqueous polyurethane
dispersant composition comprising a urea-terminated polyurethane as
generally set forth above, wherein the polyurethane contains a sufficient
amount of ionic functionality in order to render the polyurethane
dispersed particles dispersible in the continuous phase of the
dispersion. Preferably, the polyurethane dispersant is an
ionically-stabilized polyurethane polymer.

[0041] The invention also relates to a method of preparing a stable
dispersion of particles such as pharmaceuticals and colorants. The first
step in the preparation is preparing an aqueous dispersion of an aqueous
urea terminated polyurethane composition comprising the steps:

[0043] (b) contacting (i), (ii) and (iii) in the presence of a
water-miscible organic solvent to form an isocyanate-functional
polyurethane prepolymer;

[0044] (c) adding water to form an aqueous dispersion; and

[0045] (d) prior to, concurrently with or subsequent to step (c),
chain-terminating the isocyanate-functional prepolymer with a primary or
secondary amine

[0046] The diol, diisocyanate and hydrophilic reactant may be added
together in any order.

[0047] The chain terminating amine is typically added prior to addition of
water in an amount to react with substantially any remaining isocyanate
functionality. The chain terminating amine is preferably a nonionic
secondary amine.

[0048] If the hydrophilic reactant contains ionizable groups then, at the
time of addition of water (step (c)), the ionizable groups must be
ionized by adding acid or base (depending on the type of ionizable group)
in an amount such that the polyurethane can be stably dispersed.

[0049] Preferably, at some point during the reaction (generally after
addition of water and after chain extension), the organic solvent is
substantially removed under vacuum to produce an essentially solvent-free
dispersion.

[0050] After the polyurethane dispersion is prepared it is used in the
dispersion of particles by known dispersion techniques.

[0051] In accordance with another aspect of the present invention, there
is provided an aqueous colored ink jet ink comprising an aqueous colorant
dispersion as described above, having from about 0.1 to about 10 wt %
pigment based on the total weight of the ink, a weight ratio of colorant
to polyurethane dispersant of from about 0.5 to about 6, a surface
tension in the range of about 20 dyne/cm to about 70 dyne/cm at
25° C., and a viscosity of lower than about 30 cP at 25° C.

[0052] In still another aspect of the present invention, there is provided
an ink set comprising at least one cyan ink, at least one magenta ink and
at least one yellow ink, wherein at least one of the inks is an aqueous
pigmented ink jet ink as set forth above and described in further detail
below.

[0053] The continuous phase of the aqueous dispersion, in addition to
water, may further comprise water-miscible organic solvent. A preferred
level of organic solvent is from about 0 wt % to about 30 wt %, based on
the weight of the continuous phase.

[0054] The dispersed phase of the aqueous dispersion is preferably from
about 0.5 wt % to about 30 wt % of the total weight of the dispersion.

[0055] The polyurethane dispersants are in of themselves aqueous
dispersions of urea terminated polyurethanes based on diols and polyether
diols shown in Structure II above. These polyurethane dispersants
potentially offer a novel and unique balance of properties including
improved dispersibility, hydrophilicity, flexibility, and toughness.
These properties can impart new improved to the particles the
polyurethanes disperse. Also improved dispersion processes can be the
result of these new urea terminated polyurethanes. The use of these
polyether diols in the urea terminated polyurethane provides improved
water resistance and lower melting point compared to polyethylene glycol
(PEG). These urea terminated polyurethane dispersant compositions are
more flexible, more dispersible and have improved interactions with
pigments and other components than polyurethanes derived from polyethyene
glycol (PEG). For the polyurethane (PUD) aqueous dispersions, the use of
the urea-terminated polyurethane dispersant with diols and polyether
diols (Structure II) also offers new balance of properties.

[0056] These polyurethane dispersants are effective dispersants for
pigments, pharmaceuticals and other small particles.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0057] All publications, patent applications, patents and other references
mentioned herein, if not otherwise indicated, are incorporated by
reference herein for all purposes as if fully set forth.

[0058] Unless otherwise defined, all technical and scientific terms used
herein have the same meaning as commonly understood by one of ordinary
skill in the art to which this invention belongs. In case of conflict,
the present specification, including definitions, will control.

[0061] When an amount, concentration, or other value or parameter is given
as either a range, preferred range or a list of upper preferable values
and lower preferable values, this is to be understood as specifically
disclosing all ranges formed from any pair of any upper range limit or
preferred value and any lower

[0062] range limit or preferred value, regardless of whether ranges are
separately disclosed. Where a range of numerical values is recited
herein, unless otherwise stated, the range is intended to include the
endpoints thereof, and all integers and fractions within the range. It is
not intended that the scope of the invention be limited to the specific
values recited when defining a range.

[0063] When the term "about" is used in describing a value or an end-point
of a range, the disclosure should be understood to include the specific
value or end-point referred to.

[0064] As used herein, the terms "comprises," "comprising," "includes,"
"including," "has," "having" or any other variation thereof, are intended
to cover a non-exclusive inclusion. For example, a process, method,
article, or apparatus that comprises a list of elements is not
necessarily limited to only those elements but may include other elements
not expressly listed or inherent to such process, method, article, or
apparatus. Further, unless expressly stated to the contrary, "or" refers
to an inclusive or and not to an exclusive or. For example, a condition A
or B is satisfied by any one of the following: A is true (or present) and
B is false (or not present), A is false (or not present) and B is true
(or present), and both A and B are true (or present).

[0065] Use of "a" or "an" are employed to describe elements and components
of the invention. This is done merely for convenience and to give a
general sense of the invention. This description should be read to
include one or at least one and the singular also includes the plural
unless it is obvious that it is meant otherwise.

[0066] The materials, methods, and examples herein are illustrative only
and, except as specifically stated, are not intended to be limiting.
Although methods and materials similar or equivalent to those described
herein can be used in the practice or testing of the present invention,
suitable methods and materials are described herein.

Urea-Terminated Polyurethanes Dispersants

[0067] The polyurethane dispersant is a urea terminated polyurethane of
the Structure I).

##STR00003## [0068] R1=alkyl, substituted alkyl, substituted
alkyl/aryl from a diisocyanate, [0069] R2=alkyl,
substituted/branched alkyl from a diol, [0070] R3=ahydrogen; alkyl;
a non-isocyanate reactive substituted, isocyanate reactive substituted,
or branched alkyl from the amine terminating group; [0071]
R4=hydrogen; alkyl; a non-isocyanate reactive substituted,
isocyanate reactive substituted, or branched alkyl from the amine
terminating group; [0072] where the isocyanate reactive group is selected
from hydroxyl, carboxyl, mercapto, or amido; [0073] n=2 to 30; [0074] and
where R2=Z1 or Z2 and at least one Z1 and at least
one Z2 must be present in the polyurethane composition:

[0074] ##STR00004## [0075] p greater than or equal to 1, [0076] when
p=1, m greater than or equal to 3 to about 30, [0077] when p=2 or
greater, m greater than or equal to 3 to about 12; [0078] R5,
R6=hydrogen, alkyl, substituted alkyl, aryl; where the R5 is
the same or different with each R5 and R6 substituted methylene
group where R5 and R5 or R6 can be joined to form a cyclic
structure; [0079] Z2 is a diol substituted with an ionic group;

[0080] wherein the urea content of the urea-terminated polyurethane is at
least 2 wt % of the polyurethane and at most about 14 wt % of the
polyurethane,

[0081] and the colorant is selected from pigments and disperse dyes or
combinations of pigments and disperse dyes

[0082] Structure I denotes the urea terminated polyurethane dispersant and
Structure II denotes the diol and polyether diol that is a building block
for Structure I. When p is 1 a diol is the primary isocyanate reactive
group and when p is greater than one the diol is characterized as a
polyether diol.

[0083] The invention also relates to a method of preparing a stable
dispersion of particles such as pharmaceuticals and colorants, especially
pigments. The first step in the preparation is preparing an aqueous
dispersion of an aqueous urea terminated polyurethane comprising the
steps:

[0085] (b) reacting (i), (ii) and (iii) in the presence of a
water-miscible organic solvent to form an isocyanate-functional
polyurethane prepolymer;

[0086] (c) adding water to form an aqueous dispersion; and

[0087] (d) prior to, concurrently with or subsequent to step (c),
chain-terminating the isocyanate-functional prepolymer with a primary or
secondary amine

[0088] The chain terminating amine is typically added prior to addition of
water in an amount to react with substantially any remaining isocyanate
functionality. The chain terminating amine is preferably a nonionic
secondary amine.

[0089] The diol, diisocyanate and hydrophilic reactant may be added
together in any order.

[0090] If the hydrophilic reactant contains ionizable groups then, at the
time of addition of water (step (c)), the ionizable groups must be
ionized by adding acid or base (depending on the type of ionizable group)
in an amount such that the polyurethane can be stably dispersed.

[0091] Preferably, at some point during the reaction (generally after
addition of water and after chain extension), the organic solvent is
substantially removed under vacuum to produce an essentially solvent-free
dispersion.

[0092] After the polyurethane dispersion is prepared it is used in the
dispersion of particles by known dispersion techniques. The key features
of the polyurethane dispersant are the diol and/or polyether diol and the
monofunctional amine which results in the urea termination. Without being
bound by theory, these polyurethanes dispersants perform better as
dispersants for pigments etc. Also, the diol and/or polyether diol/urea
termination combination seems to produce a relatively pure polyurethane
that does not have contamination and/or extensive crosslinking that can
lead to poorer performance dispersing pigments and other particles.

[0093] The urea-terminated polyurethanes are dispersants for particles,
such as pigments. In this case, the polyurethane is either 1) utilized as
a dissolved polyurethane in a compatible solvent where the initial
polyurethane/particle mixture is prepared and then processed using
dispersion equipment to produce the aqueous polyurethane dispersed
particle; or 2) the polyurethane dispersion and the particle dispersed
are mixed in a compatible solvent system which, in turn is processed
using dispersion equipment to produce the aqueous polyurethane dispersed
particle where the polyurethane is the dispersant.

[0094] It should be understood that the process of used to prepare the
polyurethane generally results in a urea-terminated polyurethane polymer
of the above structure being present in the final product. However, it is
understood that the final product will typically be a mixture of
products, of which a portion is the above urea terminated polyurethane
polymer, the other portion being a normal distribution of other polymer
products and may contain varying ratios of unreacted monomers. The
heterogeneity of the resultant polymer will depend on the reactants
selected and reactant conditions chosen, as will be apparent to those
skilled in the art.

[0095] A preferred use of the urea terminated polyurethane dispersants is
to make ink jet ink with dispersed colorants, especially pigments.
Optional formulation parameters for the ink jet inks include:

[0096] a) the polyurethane dispersant where a polyether diol of Structure
II which is at least 50 weight percent of the polyether diol;

[0097] b) the polyurethane dispersant where a polyether diol of Structure
II which has a number average molecular weight of 200 to 5000.

[0098] c) the polyurethane dispersant where a polyether diol of Structure
II which has m=3 or 4.

[0099] d) the polyurethane dispersant where R5 and R6 of the polyurethane
dispersant are hydrogen.

[0100] e) the polyurethane dispersant where the polyether diol of
Structure II m=3 and the ether is group is derived from biological
sources.

[0101] f) the polyurethane dispersant where Groups R3 and R4 of the
polyurethane dispersant are substituted with nonionic hydrophilic groups.

[0102] g) the polyurethane dispersant where Groups R3 and R4 of the
polyurethane dispersant are methoxyethyl.

[0103] h). d) the polyurethane dispersant where Groups R3 and R4 of the
polyurethane dispersant are alkyl.

Diol and Polyether Diol Component

[0104] The diol component can either be based on alpha, omega dialcohol or
diols (p=1) with at least 3 methylene groups and less than or equal to 30
methylene groups (m=3 to about 30) or a polyether diol (p is greater than
1) with 3 to 12 methylene groups (m=3 to about 12). The diol and
polyether diol can be used separately or in mixtures. The amount of
diol:polyether diol ranges from 0:100 to 100:0.

[0105] In one embodiment, the diol and/or polyether diol shown in
Structure (II) may be blended with other oligomeric and/or polymer
polyfunctional isocyanate-reactive compounds such as, for example,
polyols, polyamines, polythiols, polythioamines, polyhydroxythiols and
polyhydroxylamines. When blended, it is preferred to use di-functional
components and, more preferably, one or more diols including, for
example, polyether diols, polyester diols, polycarbonate diols,
polyacrylate diols, polyolefin diols and silicone diols.

[0106] When p is greater than 1 the polyether diol shown in Structure (II)
are oligomers and polymers in which at least 50% of the repeating units
have 3 to 12 methylene groups in the ether chemical groups. More
preferably from about 75% to 100%, still more preferably from about 90%
to 100%, and even more preferably from about 99% to 100%, of the
repeating units are 3 to 12 methylene groups in the ether chemical groups
(in Structure (II) m=3-12). The preferable number of methylene groups are
3 or 4. The polyether diol shown in Structure (II) can be prepared by
polycondensation of monomers comprising alpha, omega diols where m=3-12,
thus resulting in polymers or copolymers containing the structural
linkage shown above. As indicated above, at least 50% of the repeating
units are 3 to 12 methylene ether units.

[0107] The oligomers and polymers based on the polyether diol {where p is
greater than 1} shown in Structure (II), have from 2 to about 50 of the
ether diol repeating groups shown in Structure (II); more preferable
about 5 to about 20 of the ether diol repeating groups shown in Structure
(II), where p denotes the number of repeating groups. In structure (II)
R5 and R6 are hydrogen, alkyl, substituted alkyl, aryl; where
the R5 and R6 are the same or different with each substituted
methylene group and where R5 and R6 can be joined to form a
cyclic structure. The substituted alkyl group preferably does not contain
isocyanate reactive groups except as described below where a limited
amount of trihydric alcohols can be allowed. In general, the substituted
alkyls are intended to be inert during the polyurethane preparation.

[0108] In addition to the 3 to 12 methylene ether units, lesser amounts of
other units, such as other polyalkylene ether repeating units derived
from ethylene oxide and propylene oxide may be present. The amount of the
ethylene glycols and 1,2-propylene glycols which are derived from
epoxides such as ethylene oxide, propylene oxide, butylene oxide, etc are
limited to less than 10% of the total polyether diol weight. A preferred
polyether diol is derived from 1,3-propanediol. The employed PO3G may be
obtained by any of the various well known chemical routes or by
biochemical transformation routes. Preferably, the 1,3-propanediol is
obtained biochemically from a renewable source ("biologically-derived"
1,3-propanediol). The description of this biochemically obtained
1,3-propanediol can be found co-owned and co-pending U.S. patent
application Ser. No. 11/782,098 (filed Jul. 24, 2007), the disclosure of
which is incorporated by reference herein for all purposes as if fully
set forth

[0109] For the diol of Structure (II) (p=1) the biochemically derived
material described above is the preferred 1,3-propanediol.

[0110] The starting material for making the diol will depend on the
desired polyether diol of Structure II (p is greater than 1),
availability of starting materials, catalysts, equipment, etc., and
comprises "1,3 to 1,12-diol reactant." By "1,3 to 1,12-diol reactant" is
meant 1,3 to 1,12-diol, and oligomers and prepolymers of 1,3 to 1,12-diol
preferably having a degree of polymerization of 2 to 50, and mixtures
thereof. In some instances, it may be desirable to use up to 10% or more
of low molecular weight oligomers where they are available. Thus,
preferably the starting material comprises 1,3 to 1,12-diol and the dimer
and trimer thereof. A particularly preferred starting material is
comprised of about 90% by weight or more 1,3 to 1,12-diol, and more
preferably 99% by weight or more 1,3 to 1,12-diol, based on the weight of
the 1,3 to 1,12-diol reactant.

[0111] As indicated above, the polyether diol shown in Structure (II) (p
greater than 1) may contain lesser amounts of other polyalkylene ether
repeating units in addition to the 3-12 methylene ether units. The
monomers for use in preparing poly(3-12)methylene ether glycol can,
therefore, contain up to 50% by weight (preferably about 20 wt % or less,
more preferably about 10 wt % or less, and still more preferably about 2
wt % or less), of comonomer diols in addition to the 1,3-propanediol
reactant. Comonomer diols that are suitable for use in the process
include aliphatic diols, for example, ethylene glycol, 1,6-hexanediol,
1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol,
1,12-dodecanediol, 3,3,4,4,5,5-hexafluoro-1,5-pentanediol,
2,2,3,3,4,4,5,5-octafluoro-1,6-hexanediol, and
3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10-hexadecafluoro-1,12-dodecanediol;
cycloaliphatic diols, for example, 1,4-cyclohexanediol,
1,4-cyclohexanedimethanol and isosorbide; and polyhydroxy compounds, for
example, glycerol, trimethylolpropane, and pentaerythritol. The polyether
diol shown in Structure (II) useful in practicing this invention can
contain small amounts of other repeat units, for example, from aliphatic
or aromatic diacids or diesters, such as described in U.S. Pat. No.
6,608,168 (the disclosure of which is incorporated by reference herein
for all purposes as if fully set forth). This type of the polyether diol
shown in Structure (II) can also be called a "random polymethylene ether
ester", and can be prepared by polycondensation of 1,3 to 1,12-diol
reactant and about 10 to about 0.1 mole % of aliphatic or aromatic diacid
or esters thereof, such as terephthalic acid, isophthalic acid, bibenzoic
acid, naphthalic acid, bis(p-carboxyphenyl)methane, 1,5-naphthalene
dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, 2,7-naphthalene
dicarboxylic acid, 4,4'-sulfonyl dibenzoic acid, p-(hydroxyethoxy)benzoic
acid, and combinations thereof, and dimethyl terephthalate, bibenzoate,
isophthlate, naphthalate and phthalate; and combinations thereof. Of
these, terephthalic acid, dimethyl terephthalate and dimethyl
isophthalate are preferred.

[0112] The preferred, the polyether diol shown in Structure (II) (p is
greater than 1) for use in the invention have a number average molecular
weight (Mn) in the range of about 200 to about 5000, and more
preferably from about 240 to about 3600. Blends of the polyether diol
shown in Structure (II) s can also be used. For example, the polyether
diol shown in Structure (II) can comprise a blend of a higher and a lower
molecular weight polyether diol shown in Structure (II) preferably
wherein the higher molecular weight polyether diol shown in Structure
(II) has a number average molecular weight of from about 1000 to about
5000, and the lower molecular weight, the polyether diol shown in
Structure (II) has a number average molecular weight of from about 200 to
about 750. The Mn of the blended polyether diol shown in Structure
(II) will preferably still be in the range of from about 250 to about
3600. The polyether diol shown in Structure (II) s preferred for use
herein are typically polydisperse polymers having a polydispersity (i.e.
Mw/Mn) of preferably from about 1.0 to about 2.2, more
preferably from about 1.2 to about 2.2, and still more preferably from
about 1.5 to about 2.1. The polydispersity can be adjusted by using
blends of the polyether diol shown in Structure (II).

[0113] The polyether diol shown in Structure (II) for use in the present
invention preferably have a color value of less than about 100 APHA, and
more preferably less than about 50 APHA.

Other Isocyanate-Reactive Components

[0114] As indicated above, the polyether diol shown in Structure (II) may
be blended with other polyfunctional isocyanate-reactive components, most
notably oligomeric and/or polymeric polyols.

[0115] Suitable other diols contain at least two hydroxyl groups, and
preferably have a molecular weight of from about 60 to about 6000. Of
these, the polymeric other diols are best defined by the number average
molecular weight, and can range from about 200 to about 6000, preferably
from about 800 to about 3000, and more preferably from about 1000 to
about 2500. The molecular weights can be determined by hydroxyl group
analysis (OH number). An example of a suitable other diol is
1,3-dihydroxyethyl dimethyl hydantoin.

[0116] Examples of polymeric polyols include polyesters, polyethers,
polycarbonates, polyacetals, poly(meth)acrylates, polyester amides,
polythioethers and mixed polymers such as a polyester-polycarbonates
where both ester and carbonate linkages are found in the same polymer. A
combination of these polymers can also be used. For examples, a polyester
polyol and a poly(meth)acrylate polyol may be used in the same
polyurethane synthesis.

[0117] Suitable polyester polyols include reaction products of polyhydric,
preferably dihydric alcohols to which trihydric alcohols may optionally
be added, and polybasic (preferably dibasic) carboxylic acids. Trihydic
alcohols are limited to at most about 2 weight % such that some branching
can occur but no significant crosslinking would occur, and may be used in
cases in which modest branching of the NCO prepolymer or polyurethane is
desired. Instead of these polycarboxylic acids, the corresponding
carboxylic acid anhydrides or polycarboxylic acid esters of lower
alcohols or mixtures thereof may be used for preparing the polyesters.

[0119] Preferable polyester diols for blending with the polyol shown in
Structure (II) are hydroxyl terminated poly(butylene adipate),
poly(butylene succinate), poly(ethylene adipate), poly(1,2-propylene
adipate), poly(trimethylene adipate), poly(trimethylene succinate),
polylactic acid ester diol and polycaprolactone diol. Other hydroxyl
terminated polyester diols are copolyethers comprising repeat units
derived from a diol and a sulfonated dicarboxylic acid and prepared as
described in U.S. Pat. No. 6,316,586 (the disclosure of which is
incorporated by reference herein for all purposes as if fully set forth).
The preferred sulfonated dicarboxylic acid is 5-sulfo-isophthalic acid,
and the preferred diol is 1,3-propanediol.

[0120] Suitable polyether polyols are obtained in a known manner by the
reaction of starting compounds that contain reactive hydrogen atoms with
alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide,
styrene oxide, tetrahydrofuran, epichlorohydrin or mixtures of these. It
is preferred that the polyethers do not contain more than about 10% by
weight of ethylene oxide units. More preferably, polyethers obtained
without the addition of ethylene oxide are used. Suitable starting
compounds containing reactive hydrogen atoms include the polyhydric
alcohols set forth for preparing the polyester polyols and, in addition,
water, methanol, ethanol, 1,2,6-hexane triol, 1,2,4-butane triol,
trimethylol ethane, pentaerythritol, mannitol, sorbitol, methyl
glycoside, sucrose, phenol, isononyl phenol, resorcinol, hydroquinone,
1,1,1- and 1,1,2-tris-(hydroxylphenyl)-ethane, dimethylolpropionic acid
or dimethylolbutanoic acid.

[0121] Polyethers that have been obtained by the reaction of starting
compounds containing amine compounds can also be used. Examples of these
polyethers as well as suitable polyhydroxy polyacetals, polyhydroxy
polyacrylates, polyhydroxy polyester amides, polyhydroxy polyamides and
polyhydroxy polythioethers, are disclosed in U.S. Pat. No. 4,701,480 (the
disclosure of which is incorporated by reference herein for all purposes
as if fully set forth).

[0122] Polycarbonates containing hydroxyl groups include those known, per
se, such as the products obtained from the reaction of diols such as
propanediol-(1,3), butanediol-(1,4) and/or hexanediol-(1,6), diethylene
glycol, triethylene glycol or tetraethylene glycol, higher polyether
diols with phosgene, diarylcarbonates such as diphenylcarbonate,
dialkylcarbonates such as diethylcarbonate or with cyclic carbonates such
as ethylene or propylene carbonate. Also suitable are polyester
carbonates obtained from the above-mentioned polyesters or polylactones
with phosgene, diaryl carbonates, dialkyl carbonates or cyclic
carbonates.

[0124] Poly(meth)acrylates containing hydroxyl groups include those common
in the art of addition polymerization such as cationic, anionic and
radical polymerization and the like. Examples are alpha-omega diols. An
example of these type of diols are those which are prepared by a "living"
or "control" or chain transfer polymerization processes which enables the
placement of one hydroxyl group at or near the termini of the polymer.
U.S. Pat. No. 6,248,839 and U.S. Pat. No. 5,990,245 (the disclosures of
which are incorporated by reference herein for all purposes as if fully
set forth) have examples of protocol for making terminal diols. Other
di-NCO reactive poly(meth)acrylate terminal polymers can be used. An
example would be end groups other than hydroxyl such as amino or thiol,
and may also include mixed end groups with hydroxyl.

[0125] Polyolefin diols are available from Shell as KRATON LIQUID L and
Mitsubishi Chemical as POLYTAIL H.

[0126] Silicone glycols are well known, and representative examples are
described in U.S. Pat. No. 4,647,643, the disclosure of which is
incorporated by reference herein for all purposes as if fully set forth.

[0127] Other optional compounds for preparing the NCO prepolymer include
lower molecular weight, at least difunctional NCO-reactive compounds
having an average molecular weight of up to about 400. Examples include
the dihydric and higher functional alcohols, which have previously been
described for the preparation of the polyester polyols and polyether
polyols.

[0128] In addition to the above-mentioned components, which are preferably
difunctional in the isocyanate polyaddition reaction, mono-functional and
even small portions of trifunctional and higher functional components
generally known in polyurethane chemistry, such as trimethylolpropane or
4-isocyanantomethyl-1,8-octamethylene diisocyanate, may be used in cases
in which branching of the NCO prepolymer or polyurethane is desired.

[0129] It is, however, preferred that the NCO-functional prepolymers
should be substantially linear, and this may be achieved by maintaining
the average functionality of the prepolymer starting components at or
below 2:1.

[0130] Similar NCO reactive materials can be used as described for hydroxy
containing compounds and polymers, but which contain other NCO reactive
groups. Examples would be dithiols, diamines, thioamines and even
hydroxythiols and hydroxylamines. These can either be compounds or
polymers with the molecular weights or number average molecular weights
as described for the polyols.

Chain Termination Reactant

[0131] The terminating agent is a primary or secondary monoamine which is
added to make the urea termination. In Structure (I) the terminating
agent is shown as R3(R4)N-- substituent on the polyurethane.
The substitution pattern for R3 and R4 include hydrogen, alkyl,
a substituted/branched alkyl, isocyanate reactive where the substituent
can be an isocyanate reactive group selected from hydroxyl, carboxyl,
mercapto, amido and other ones which have less isocyanate reactivity than
primary or secondary amine. At least one of the R3 and R4 must
be other than hydrogen.

[0132] The amount of chain terminator employed should be approximately
equivalent to the unreacted isocyanate groups in the prepolymer. The
ratio of active hydrogens from amine in the chain terminator to
isocyanate groups in the prepolymer preferably being in the range from
about 1.0:1 to about 1.2:1, more preferably from about 1.0:1.1 to about
1.1:1, and still more preferably from about 1.0:1.05 to about 1.1:1, on
an equivalent basis. Although any isocyanate groups that are not
terminated with an amine can react with other isocyanate reactive
functional group and water the ratios of chain termination to isocyanate
group is chosen to assure urea termination. Amine termination of the
polyurethane is avoided by the choice and amount of chain terminating
agent leading to a urea terminated polyurethane which has improved
molecular weight control and improved properties as a particle
dispersant.

[0133] Aliphatic primary or secondary monoamines are preferred. Example of
monoamines useful as chain terminators include but are not restricted to
butylamine, hexylamine, 2-ethylhexyl amine, dodecyl amine, diisopropanol
amine, stearyl amine, dibutyl amine, dinonyl amine, bis(2-ethylhexyl)
amine, diethylamine, bis(methoxyethyl)amine, N-methylstearyl amine,
diethanolamine and N-methyl aniline. A preferred isocyanate reactive
chain terminator is bis(methoxyethyl)amine(BMEA). The
bis(methoxyethyl)amine is part of a preferred class of urea terminating
reactant where the substituents are non reactive in the isocyanate
chemistry, but are nonionic hydrophilic groups. This nonionic hydrophilic
group provides the urea terminated polyether diol polyurethane with more
water compatible.

[0134] Any primary or secondary monoamines substituted with less
isocyanate reactive groups may be used as chain terminators. Less
isocyanate reactive groups could be hydroxyl, carboxyl, amide and
mercapto. Example of monoamines useful as chain terminators include but
are not restricted to monoethanolamine, 3-amino-1-propanol,
isopropanolamine, N-ethylethanolamine, diisopropanolamine, 6-aminocaproic
acid, 8-aminocaprylic acid, 3-aminoadipic acid, and lysine. Chain
terminating agents may include those with two less isocyanate reactive
groups such as glutamine. A preferred isocyanate reactive chain
terminator is diethanolamine. The diethanolamine is part of a preferred
class of urea terminating reactant where the substituents are hydroxyl
functionalities which can provide improved pigment wetting. The relative
reactivity of the amine versus the less isocyanate reactive group and the
mole ratios of NCO and the chain terminating amine produce the urea
terminated polyurethane.

[0135] The urea content of the urea-terminated polyurethane in weight
percent of the polyurethane is determined by dividing the mass of chain
terminator by the sum of the other polyurethane components including the
chain terminating agent. The urea content is from about 0.75 wt % to
about 14 wt %. The urea content is preferably from about 2.5 wt % to
about 10.5 wt %. The 0.75 wt % occurs when the polyether diols used are
large, for instance Mn is greater than about 4000 and/or the
molecular weight of the isocyanate is high.

Polyisocyanate Component

[0136] Suitable polyisocyanates are those that contain either aromatic,
cycloaliphatic or aliphatic groups bound to the isocyanate groups.
Mixtures of these compounds may also be used. Preferred are compounds
with isocyanates bound to a cycloaliphatic or aliphatic moieties. If
aromatic isocyanates are used, cycloaliphatic or aliphatic isocyanates
are preferably present as well. In Structure I, R1 can be preferably
substituted with aliphatic groups.

[0137] Diisocyanates are preferred, and any diisocyanate useful in
preparing polyurethanes and/or polyurethane-ureas from polyether glycols,
diisocyanates and diols or amine can be used in this invention.

[0139] Small amounts, preferably less than about 3 wt % based on the
weight of the diisocyanate, of monoisocyanates or polyisocyanates can be
used in mixture with the diisocyanate. Examples of useful monoisocyanates
include alkyl isocyanates such as octadecyl isocyanate and aryl
isocyanates such as phenyl isocyanate. Example of a polyisocyanate are
triisocyanatotoluene HDI trimer (Desmodur 3300), and polymeric MDI
(Mondur MR and MRS).

Ionic Reactants

[0140] The hydrophilic reactant contains ionic and/or ionizable groups
(potentially ionic groups). Preferably, these reactants will contain one
or two, more preferably two, isocyanate reactive groups, as well as at
least one ionic or ionizable group. In the structural description of the
urea terminated polyether polyurethane described herein the reactant
containing the ionic group is designated as Z2.

[0141] Examples of ionic dispersing groups include carboxylate groups
(--COOM), phosphate groups (--OPO3 M2), phosphonate groups
(--PO3 M2), sulfonate groups (--SO3 M), quaternary
ammonium groups (--NR3 Y, wherein Y is a monovalent anion such as
chlorine or hydroxyl), or any other effective ionic group. M is a cation
such as a monovalent metal ion (e.g., Na.sup.+, K.sup.+, Li.sup.+, etc.),
H.sup.+, NR4.sup.+, and each R can be independently an alkyl,
aralkyl, aryl, or hydrogen. These ionic dispersing groups are typically
located pendant from the polyurethane backbone.

[0142] The ionizable groups in general correspond to the ionic groups,
except they are in the acid (such as carboxyl --COOH) or base (such as
primary, secondary or tertiary amine --NH2, --NRH, or --NR2)
form. The ionizable groups are such that they are readily converted to
their ionic form during the dispersion/polymer preparation process as
discussed below.

[0143] The ionic or potentially ionic groups are chemically incorporated
into the polyurethane in an amount to provide an ionic group content
(with neutralization as needed) sufficient to render the polyurethane
dispersible in the aqueous medium of the dispersion. Typical ionic group
content will range from about 10 up to about 210 milliequivalents (meq),
preferably from about 20 to about 140 meq., per 100 g of polyurethane,
and most preferably less than about 90 meq per 100 g of urea terminated
polyurethane.

[0144] Suitable compounds for incorporating these groups include (1)
monoisocyanates or diisocyanates which contain ionic and/or ionizable
groups, and (2) compounds which contain both isocyanate reactive groups
and ionic and/or ionizable groups. In the context of this disclosure, the
term "isocyanate reactive groups" is taken to include groups well known
to those of ordinary skill in the relevant art to react with isocyanates,
and preferably hydroxyl, primary amino and secondary amino groups.

[0146] With respect to compounds which contain isocyanate reactive groups
and ionic or potentially ionic groups, the isocyanate reactive groups are
typically amino and hydroxyl groups. The potentially ionic groups or
their corresponding ionic groups may be cationic or anionic, although the
anionic groups are preferred. Preferred examples of anionic groups
include carboxylate and sulfonate groups. Preferred examples of cationic
groups include quaternary ammonium groups and sulfonium groups.

[0147] The neutralizing agents for converting the ionizable groups to
ionic groups are described in the preceding incorporated publications,
and are also discussed hereinafter. Within the context of this invention,
the term "neutralizing agents" is meant to embrace all types of agents
that are useful for converting ionizable groups to the more hydrophilic
ionic (salt) groups.

[0148] In the case of anionic group substitution, the groups can be
carboxylic acid groups, carboxylate groups, sulphonic acid groups,
sulphonate groups, phosphoric acid groups and phosphonate groups, The
acid salts are formed by neutralizing the corresponding acid groups
either prior to, during or after formation of the NCO prepolymer,
preferably after formation of the NCO prepolymer.

[0149] Suitable compounds for incorporating carboxyl groups are described
in U.S. Pat. No. 3,479,310, U.S. Pat. No. 4,108,814 and U.S. Pat. No.
4,408,008, the disclosures of which are incorporated by reference herein
for all purposes as if fully set forth. The neutralizing agents for
converting the carboxylic acid groups to carboxylate salt groups are
described in the preceding incorporated publications, and are also
discussed hereinafter. Within the context of this invention, the term
"neutralizing agents" is meant to embrace all types of agents that are
useful for converting carboxylic acid groups to the more hydrophilic
carboxylate salt groups. In like manner, sulphonic acid groups,
sulphonate groups, phosphoric acid groups, and phosphonate groups can be
neutralized with similar compounds to their more hydrophilic salt form.

[0152] Especially preferred acids are those of the above-mentioned
structure wherein x=2 and y=1. These dihydroxy alkanoic acids are
described in U.S. Pat. No. 3,412,054, the disclosure of which is
incorporated by reference herein for all purposes as if fully set forth.
Especially preferred dihydroxy alkanoic acids are the
alpha,alpha-dimethylol alkanoic acids represented by the Structure (III):
wherein Q' is hydrogen

##STR00005##

or an alkyl group containing 1 to 8 carbon atoms. The most preferred
compound is alpha,alpha-dimethylol propionic acid, i.e., wherein Q' is
methyl in the above formula. These dihydroxy alkanoic acids are described
in U.S. Pat. No. 3,412,054, the disclosure of which is incorporated by
reference herein for all purposes as if fully set forth. The preferred
group of dihydroxy alkanoic acids are the α,α-dimethylol
alkanoic acids represented by the structure
R7C--(CH2OH)2--COOH, wherein R7 is hydrogen or an
alkyl group containing 1 to 8 carbon atoms. Examples of these ionizable
diols include but are not limited to dimethylolacetic acid,
2,2'-dimethylolbutanoic acid, 2,2'-dimethylolpropionic acid, and
2,2'-dimethylolbutyric acid. The most preferred dihydroxy alkanoic acids
is 2,2'-dimethylolpropionic acid ("DMPA"). Suitable carboxylates also
include H2N--(CH2)4--CH(CO2H)--NH2, and
H2N--CH2--CH2--NH--CH2--CH2--CO2Na

[0153] When the ionic stabilizing groups are acids, the acid groups are
incorporated in an amount sufficient to provide an acid group content for
the urea-terminated polyurethane, known by those skilled in the art as
acid number (mg KOH per gram solid polymer), of at least about 6,
preferably at least about 10 milligrams KOH per 1.0 gram of polyurethane
and even more preferred 20 milligrams KOH per 1.0 gram of polyurethane,
The upper limit for the acid number (AN) is about 120, and preferably
about 90.

[0154] Suitable compounds for incorporating the previously discussed
carboxylate, sulfonate and quaternary nitrogen groups are described in
U.S. Pat. No. 3,479,310, U.S. Pat. No. 4,303,774 and U.S. Pat. No.
4,108,814, the disclosures of which are incorporated by reference herein
for all purposes as if fully set forth.

[0155] Suitable compounds for incorporating tertiary sulfonium groups are
described in U.S. Pat. No. 3,419,533, the disclosure of which is
incorporated by reference herein for all purposes as if fully set froth.
The neutralizing agents for converting the potentially ionic groups to
ionic groups are also described in those patents. Within the context of
this disclosure, the term "neutralizing agents" is meant to embrace all
types of agents which are useful for converting potentially ionic or
ionizable groups to ionic groups. Accordingly, this term also embraces
quaternizing agents and alkylating agents.

[0156] The preferred sulfonate groups for incorporation into the
polyurethanes are the diol sulfonates as disclosed in previously
incorporated U.S. Pat. No. 4,108,814.

Suitable diol sulfonate compounds also include hydroxyl terminated
copolyethers comprising repeat units derived from a diol and a sulfonated
dicarboxylic acid and prepared as described in previously incorporated
U.S. Pat. No. 6,316,586. The preferred sulfonated dicarboxylic acid is
5-sulfo-isophthalic acid, and the preferred diol is 1,3-propanediol.

[0157] Suitable sulfonates also include
H2N--CH2--CH2--NH--(CH2)r--SO3Na, where r=2
or 3; and HO--CH2--CH2--C(SO3Na)--CH2--OH. The
preferred carboxylate groups for incorporation are derived from
hydroxy-carboxylic acids of the general structure
((HO)xR8(COOH)y, wherein R8 represents a straight or
branched hydrocarbon radical containing 1 to 12 carbon atoms, and x and y
each independently represents values from 1 to 3. Examples of these
hydroxy-carboxylic acids include citric acid and tartaric acid.

[0158] In addition to the foregoing, cationic centers such as tertiary
amines with one alkyl and two alkylol groups may also be used as the
ionic or ionizable group.

[0159] When amines are used as the neutralizing agent, the chain
terminating reaction producing the urea termination is preferably
completed prior to addition of a neutralizing agent that can also behave
as an isocyanate reactive group.

[0160] In order to convert the preferred potential anionic groups to
anionic groups either before, during or after their incorporation into
the prepolymers, either volatile or nonvolatile basic materials may be
used to form the counterions of the anionic groups. Volatile bases are
those wherein at least about 90% of the base used to form the counterion
of the anionic group volatilizes under the conditions used to remove
water from the aqueous polyurethane dispersions. Nonvolatile basic
materials are those wherein at least about 90% of the base does not
volatilize under the conditions used to remove water from the aqueous
polyurethane dispersions.

[0162] Suitable nonvolatile basic materials include monovalent metals,
preferably alkali metal, more preferably lithium, sodium and potassium
and most preferably sodium, hydrides, hydroxides, carbonates or
bicarbonates. When an acid-containing diol, for example, is used as the
ionic group, a relatively mild inorganic base such as NaHCO3,
Na2(CO3), NaAc (where Ac represents acetate), NaH2PO4
and the like will assist in improving the dispersion. These inorganic
bases are relatively low in odor, and also tend not to be skin irritants.

[0163] When the potential cationic or anionic groups of the polyurethane
are neutralized, they provide hydrophilicity to the polymer and
facilitating the formation of a stable aqueous polyurethane dispersion.
The neutralization steps may be conducted (1) prior to polyurethane
formation by treating the component containing the potentially ionic
group(s), or (2) after polyurethane formation, but prior to dispersing
the polyurethane. The reaction between the neutralizing agent and the
potential anionic groups may be conducted between about 20° C. and
about 150° C., but is normally conducted at temperatures below
about 100° C., preferably between about 30° C. and about
80° C., and more preferably between about 50° C. and about
70° C., with agitation of the reaction mixture. The ionic or
potentially ionic group may be used in amount of about 2 to about 20
percent by weight solids.

[0164] The isocyanate reactive ionic reactants will preferably contain one
or two, more preferably two, isocyanate reactive groups such as amino or
hydroxyl groups, as well as at least one ionic or ionizable group such as
carboxyl, sulfonate and tertiary ammonium salts. A preferred ionic or
ionizable group is carboxyl.

[0165] The urea terminated polyurethane dispersant has a molecular weight
of about 2000 to about 30,000. Preferably the molecular weight is about
3000 to 20000.

Particles to be Dispersed

[0166] A wide variety of particles may be dispersed by the inventive urea
terminated polyurethane dispersant which include colorants,
pharmaceuticals and other particles. The colorants include organic and
inorganic pigments and disperse dyes, alone or in combination, may be
dispersed with the urea terminated polyurethane dispersant to prepare an
ink, especially an inkjet ink. The term "pigment" as used herein means an
insoluble colorant that requires it to be dispersed with a dispersant and
processed under dispersive conditions with the dispersant present. The
dispersion process results in a stable dispersed pigment.

[0167] The pigment used with the inventive urea terminated polyurethane
dispersants do not include self-dispersed pigments.

[0168] The polyurethane dispersed pigment particles are sufficiently small
to permit free flow of the ink through the ink jet printing device,
especially at the ejecting nozzles that usually have a diameter ranging
from about 10 micron to about 50 micron. The particle size also has an
influence on the pigment dispersion stability, which is critical
throughout the life of the ink. Brownian motion of minute particles will
help prevent the particles from flocculation. It is also desirable to use
small particles for maximum color strength and gloss. The range of useful
particle size is typically about 0.005 micron to about 15 micron.
Preferably, the pigment particle size should range from about 0.005 to
about 5 micron and, most preferably, from about 0.005 to about 1 micron.
The average particle size as measured by dynamic light scattering is less
than about 500 nm, preferably less than about 300 nm.

[0169] The selected pigment(s) may be used in dry or wet form. For
example, pigments are usually manufactured in aqueous media and the
resulting pigment is obtained as water-wet presscake. In presscake form,
the pigment is not agglomerated to the extent that it is in dry form.
Thus, pigments in water-wet presscake form do not require as much
deflocculation in the process of preparing the inks as pigments in dry
form. Representative commercial dry pigments are listed in previously
incorporated U.S. Pat. No. 5,085,698.

[0170] In the case of organic pigments, the ink may contain up to
approximately 30%, preferably about 0.1 to about 25%, and more preferably
about 0.25 to about 10%, pigment by weight based on the total ink weight.
If an inorganic pigment is selected, the ink will tend to contain higher
weight percentages of pigment than with comparable inks employing organic
pigment, and may be as high as about 75% in some cases, since inorganic
pigments generally have higher specific gravities than organic pigments.

[0171] The urea terminated polyurethane polymer dispersant is preferably
present in the range of about 0.1 to about 20%, more preferably in the
range of about 0.2 to about 10%, and still more preferably in the range
of about 0.25% to about 5%, by weight based on the weight of the total
dispersion composition.

[0172] When the ionic content is low, less than about 90 meq per 100 g of
polyurethane, the urea terminated polyurethane dispersants have low salt
stability. This low salt stability is associated with the phenomena that
the pigment in the inkjet ink will crash out onto the surface of a
substrate, especially paper and produce a high optical density. The
optical density is similar to what has been obtained with self-dispersed
pigments like those described in U.S. Pat. No. 6,852,156. This document
is incorporated by reference herein for all purposes as if fully set
forth.

[0173] A new class of low salt stability polymeric dispersants was
described in US2005/0090599. This document is incorporated by reference
herein for all purposes as if fully set forth. The inventive urea
terminated polyurethanes when they have an ionic content of less than
about 90 meq per 100 g of polyurethane, also have this characteristic
property. That is, the pigment dispersion with the inventive urea
terminated polyurethanes have low salt stability. When the pigment
dispersion is tested with salt solutions as described in US2005/0090599
the urea terminated polyurethane dispersed pigment will precipitate out
of solution. The pigment dispersion with the inventive urea terminated
polyurethanes will precipitate out of solution with salt solutions of
less than 0.16 molar salt.

[0174] Unexpectedly, the urea terminated polyurethane dispersed pigment
when they have a ionic content of less than about 90 meq per 100 g of
polyurethane gives improved optical density relative to pigment dispersed
with acrylic and acrylate-based dispersants, but also give improved
Distinctness of Image (DOI) and improved gloss. This is a surprisingly
good result, with the aforementioned pigmented inks utilizing acrylic
dispersants for ink jet inks, there is an optical density/gloss (or DOI)
tradeoff. The inventive inks produce color intensity, gloss and DOI with
a significantly better balance of performance than the pigmented inks
with acrylic dispersants. Furthermore with the optical properties the
inventive inks rival inks made from dyes. The printed inventive inks have
significantly improved durability relative to dye inks.

[0175] Mixtures of urea terminated polyurethane dispersants may be used
for dispersing particles. Also, mixtures of urea terminated polyurethane
dispersant with other commonly used dispersants may be used.

Polyurethane and Polyurethane Dispersion Preparation

[0176] The process of preparing the dispersions of the invention begins
with preparation of the polyurethane, which can be prepared by mixture or
stepwise methods. The preferred physical form of the polyurethane is as a
dispersion. These urea-terminated polyether polyurethanes can behave as a
dispersant for a particle, such as a pigment. In this case, the
polyurethane is either 1.) utilized as a dissolved polyurethane in a
compatible solvent where the initial polyurethane/particle mixture is
prepared and then processed using dispersion equipment to produce the
polyurethane dispersed particle; or 2) the polyurethane dispersion and
the particle dispersed are mixed in a compatible solvent system which, in
turn is processed using dispersion equipment to produce the polyurethane
dispersed particle.

[0177] In the mixture process for preparing the urea terminated
polyurethane, a isocyanate terminated polyurethane is prepared by mixing
the polyol of Structure (II), the ionic reactant, up to 50% other diols,
and solvent, and then adding diisocyanate to the mixture. This reaction
is conducted at from about 40° C. to about 100° C., and
more preferably from about 50° C. to about 90° C. The
preferred ratio of isocyanate to isocyanate reactive groups is from about
1.3:1 to about 1.05:1, and more preferably from about 1.25:1 to about
1.1:1. This isocyanate terminated polyurethane is often called a
polyurethane prepolymer prior to the reaction with the chain terminating
agent. When the targeted percent isocyanate is reached, then the primary
or secondary amine chain terminator is added, and then base or acid is
added to neutralize ionizable moieties incorporated from the ionizable
reagent. The polyurethane solution is then converted to an aqueous
polyurethane dispersion via the addition of water under high shear. If
present, the volatile solvent can be distilled under reduced pressure or
other means.

[0178] If some cases, addition of neutralization agent, preferably
tertiary amines, may be beneficial added during early stages of the
polyurethane synthesis. Alternately, advantages may be achieved via the
addition of the neutralization agent, preferably alkali base,
simultaneously along with the water of inversion at high shear.

[0179] In the stepwise method, isocyanate terminated polyurethane is
prepared by dissolving the ionic reactant in solvent, and then adding
diisocyanate to the mixture. Once the initial percent isocyanate target
is reached, the polyol component is added. This reaction is conducted at
from about 40° C. to about 100° C., and more preferably
from about 50° C. to about 90° C. The preferred ratio of
isocyanate to isocyanate reactive groups is from about 1.3:1 to about
1.05:1, and more preferably from about 1.25:1 to about 1.1:1.
Alternately, the diols and/or polyether polyols and up to 50% other diols
may be reacted in the first step, and the ionic reactant may be added
after the initial percent isocyanate target is reached. When the final
targeted percent isocyanate is reached for the polyurethane prepolymer,
then the chain terminator is added, and then base or acid is added to
neutralize ionizable moieties incorporated from the ionizable reagent.
The polyurethane solution is then converted to an aqueous polyurethane
dispersion via the addition of water under high shear. If present, the
volatile solvent can be distilled under reduced pressure.

[0180] In all polyurethane reaction schemes if the neutralization reactant
has isocyanate reaction capability, (for example an alcohol, primary
amine or secondary amine) it cannot be added prior to the chain
terminating, urea forming amine. If the neutralization agent can function
as a chain terminating reactant according to Structure (I), then it must
be added after all of the other isocyanate reactive groups have been
reacted.

[0181] Catalysts are not necessary to prepare the polyurethanes, but may
provide advantages in their manufacture. The catalysts most widely used
are tertiary amines and organo-tin compounds such as stannous octoate,
dibutyltin dioctoate, dibutyltin dilaurate.

[0182] Preparation of the Polyurethane for Subsequent Conversion to a
dispersion is facilitated by using solvent. Suitable solvents are those
that are miscible with water and inert to isocyanates and other reactants
utilized in forming the polyurethanes. If it is desired to prepare a
solvent-free dispersion, then it is preferable to use a solvent with a
high enough volatility to allow removal by distillation. However,
polymerizable vinyl compounds may also be used as solvents, followed by
free radical polymerization after inversion, thus forming a polyurethane
acrylic hybrid dispersion. Typical solvents useful in the practice of the
invention are acetone, methyl ethyl ketone, toluene, and N-methyl
pyrollidone. Preferably the amount of solvent used in the reaction will
be from about 10% to about 50%, more preferably from about 20% to about
40% of the weight. Alternatively, the polyurethane can be prepared in a
melt with less than 5% solvent.

[0183] Process conditions for preparing the NCO containing prepolymers
have been discussed in the publications previously noted. The finished
NCO-containing prepolymer should have a isocyanate content of about 1 to
about 20%, preferably about 1 to about 10% by weight, based on the weight
of prepolymer solids.

[0185] The process conditions used for preparing the urea-terminated ether
type polyurethane of the present invention generally results in a
polyurethane polymer of Structure I being present in the final product.
However, it is understood that the final product will typically be a
mixture of products, of which a portion is the desired polyurethane
polymer, the other portion being a normal distribution of other polymer
products and may contain varying ratios of unreacted monomers. The
heterogeneity of the resultant polymer will depend on the reactants
selected and reactant conditions chosen, as will be apparent to those
skilled in the art.

Neutralization

[0186] In order to have a stable dispersion, a sufficient amount of the
ionic groups must be neutralized so that, the resulting polyurethane will
remain stably dispersed in the aqueous medium. Generally, at least about
70%, preferably at least about 80%, of the acid groups are neutralized to
the corresponding carboxylate salt groups. Alternatively, cationic groups
in the polyurethane can be quaternary ammonium groups (--NR3Y,
wherein Y is a monovalent anion such as chlorine or hydroxyl).

[0187] Suitable neutralizing agents for converting the acid groups to salt
groups include tertiary amines, alkali metal cations and ammonia.
Examples of these neutralizing agents are disclosed in previously
incorporated U.S. Pat. No. 4,701,480, as well as U.S. Pat. No. 4,501,852
(the disclosure of which is incorporated by reference herein for all
purposes as if fully set forth). Preferred neutralizing agents are the
trialkyl-substituted tertiary amines, such as triethyl amine, tripropyl
amine, dimethylcyclohexyl amine, dimethylethanol amine, and triethanol
amine and dimethylethyl amine. Substituted amines are also useful
neutralizing groups such as diethyl ethanol amine or diethanol methyl
amine.

[0188] Neutralization may take place at any point in the process. Typical
procedures include at least some neutralization of the prepolymer, which
is then chain extended/terminated in water in the presence of additional
neutralizing agent.

[0189] The polyurethane dispersion which is used as the dispersant is a
stable aqueous dispersion of polyurethane particles having a solids
content of up to about 60% by weight, preferably from about 10 to about
60% by weight, and more preferably from about 25 to about 45% by weight.
However, it is always possible to dilute the dispersions to any minimum
amount that can be used when the polyurethane is used as a dispersant.
The solids content of the resulting dispersion may be determined by
drying the sample in an oven at 150° C. for 2 hours and comparing
the weights before and after drying. The particle size is generally below
about 1.0 micron, and preferably between about 0.01 to about 0.5 micron.
The average particle size should be less than about 0.5 micron, and
preferably between about 0.01 to about 0.3 micron. The small particle
size enhances the stability of the dispersed polyurethane particles

[0190] In accordance with the present invention the term "aqueous
polyurethane dispersion" refers to aqueous dispersions of polymers
containing urethane groups, as that term is understood by those of
ordinary skill in the art. These polymers also incorporate hydrophilic
functionality to the extent required to maintain a stable dispersion of
the polymer in water. The compositions of the invention are aqueous
dispersions that comprise a continuous phase comprising water, and a
dispersed phase comprising polyurethane.

[0191] Following formation of the desired polyurethane dispersion,
preferably in the presence of solvent as discussed above, the pH may be
adjusted typically pH about 7 to 9, if necessary, to insure conversion of
ionizable groups to ionic groups. For example, if the preferred
dimethylolpropionic acid is the ionic or ionizable ingredient used in
making the polyurethane, then sufficient aqueous base is added to convert
the carboxyl groups to carboxylate anions.

[0192] Conversion to the aqueous dispersion is completed by addition of
water. If desired, solvent can then be removed partially or substantially
by distillation which can be done under reduced pressure.

[0193] Fillers, plasticizers, pigments, carbon black, silica sols, other
polymer dispersions and the known leveling agents, wetting agents,
antifoaming agents, stabilizers, and other additives known for the
desired end use, may also be incorporated into the dispersions.

Polyurethane Pigment Dispersion Preparation

[0194] The urea-terminated polyurethanes are dispersants for particles,
such as pigments. In this case, the polyurethane is either 1) utilized as
a dissolved polyurethane in a compatible solvent where the initial
polyurethane/particle mixture is prepared and then processed using
dispersion equipment to produce the aqueous polyurethane dispersed
particle; or 2) the polyurethane dispersion and the particle dispersed
are mixed in a compatible solvent system which, in turn is processed
using dispersion equipment to produce the aqueous polyurethane dispersed
particle where the polyurethane is the dispersant. While not being bound
by theory, it is assumed that the particle and the polyurethane have the
appropriate physical/chemical interactions that are required to prepare a
stable dispersion of particles especially pigments. Furthermore, it is
possible that some of the polyurethane is not bound to the pigment and
exists either as a dispersion of the polyurethane or polyurethane
dissolved in the liquid phase of the dispersion.

[0195] The urea terminated polyurethane and ink compositions of the
invention may be prepared by methods known in the art. It is generally
desirable to make the urea terminated polyurethane in a concentrated
form, which is subsequently diluted with a suitable liquid containing the
desired additives. The urea terminated polyurethane dispersion is first
prepared by premixing the selected pigment(s) and urea terminated
polyurethane polymeric dispersant(s) in an aqueous carrier medium (such
as water and, optionally, a water-miscible solvent), and then dispersing
or deflocculating the pigment. The water miscible solvent is chosen to
assure that during the particle dispersion process the polyurethane can
function as a dispersant, that is, the polyurethane becomes the
dispersant for the particle. Candidate water miscible solvents include
Dipropylene Glycol Methyl Ether, Propylene Glycol Normal Propyl Ether,
Ethylene Glycol Monobutyl Ether, Diethylene Gllycol Monobuty Ether,
Isoproyl Alcohol, 2-Pyrrolidone, Triethylene Glycol Monobutyl Ether,
tetraglyme, sulfolane, n-methylpyrrolidon, propylene carbonate. methyl
ethyl ketone, methyl isobutyl ketone, butyrolactone

[0196] The dispersing step may be accomplished in a 2-roll mill, media
mill, a horizontal mini mill, a ball mill, an attritor, or by passing the
mixture through a plurality of nozzles within a liquid jet interaction
chamber at a liquid pressure of at least 5,000 psi to produce a uniform
dispersion of the pigment particles in the aqueous carrier medium
(microfluidizer). Alternatively, the concentrates may be prepared by dry
milling the polymeric dispersant and the pigment under pressure.

[0197] The media for the media mill is chosen from commonly available
media, including zirconia, YTZ, and nylon. These various dispersion
processes are in a general sense well-known in the art, as exemplified
by, U.S. Pat. No. 5,022,592, U.S. Pat. No. 5,026,427, U.S. Pat. No.
5,310,778, U.S. Pat. No. 5,891,231, U.S. Pat. No. 5,679,138, U.S. Pat.
No. 5,976,232 and US20030089277. All of these documents are incorporated
by reference herein for all purposes as if fully set forth. Preferred are
2-roll mill, media mill, and by passing the mixture through a plurality
of nozzles within a liquid jet interaction chamber at a liquid pressure
of at least 5,000 psi.

[0198] After the milling process is complete the pigment concentrate may
be "let down" into an aqueous system. "Let down" refers to the dilution
of the concentrate with mixing or dispersing, the intensity of the
mixing/dispersing normally being determined by trial and error using
routine methodology, and often being dependent on the combination of the
polymeric dispersant, solvent and pigment. The determination of
sufficient let down conditions is needed for all combinations of the
polymeric dispersant, the solvent and the pigment.

[0199] After the urea terminated polyurethane dispersion preparation, the
amount of water-miscible solvent may be more than some ink jet
applications will tolerate. For some of the urea terminated polyurethane
dispersions, it thus may be necessary to ultrafilter the final dispersion
to reduce the amount of water-miscible solvent. To improve stability and
reduce the viscosity of the pigment dispersion, it may be heat treated by
heating from about 30° C. to about 100° C., with the
preferred temperature being about 70° C. for about 10 to about 24
hours. Longer heating does not affect the performance of the dispersion.

[0200] The amount of polymeric urea terminated polyurethane dispersants
required to stabilize the pigment is dependent upon the specific urea
terminated polyurethane dispersants, the pigment and vehicle interaction.
The weight ratio of pigment to polymeric urea terminated polyurethane
dispersants will typically range from about 0.5 to about 6. A preferred
range is about 0.75 to about 4.

[0201] While not being bound by theory, it is believed that the urea
terminated polyurethane's provide improved ink properties by the
following means. Stable aqueous dispersions are critical for inkjet inks
to assure long-lived ink cartridges and few problems with failed nozzles,
etc. It is, however, desirable for the ink to become unstable as it is
jetted onto the media so that the pigment in the ink "crashes out" onto
the surface of the media (as opposed to being absorbed into the media).
With the pigment on the surface of the media, beneficial properties of
the ink can be obtained.

[0202] The urea terminated polyurethane polymeric dispersants provide
novel dispersants that sufficiently stabilize the ink prior to jetting
(such as in the cartridge) but, as the ink is jetted onto the paper, the
pigment system is destabilized and the pigment remains on the surface of
the media. This leads to improved ink properties.

EXAMPLES

[0203] The following examples are presented for the purpose of
illustrating the invention and are not intended to be limiting. All
parts, percentages, etc., are by weight unless otherwise indicated.

[0204] The dispersions whose preparation is described in the examples
below were characterized in terms of their particle size and particle
size distribution.

[0205] Ingredients and Abbreviations

[0206] BMEA=bis(methoxyethyl)amine

[0207] DBTL=dibutyltindilaurate

[0208] DMEA=dimethylethanolamine

[0209] DMIPA=dimethylisopropylamine

[0210] DMPA=dimethylol propionic acid

[0211] DMBA=dimethylol butyric acid

[0212] EDA=ethylene diamine

[0213] EDTA=ethylenediamine tetraacetic acid

[0214] HDI=1,6-hexamethylene diisocyanate

[0215] IPDI=isophoronediisocyanate

[0216] TMDI=trimethylhexamethylene diisocyanate

[0217] TMXDI=m-tetramethylene xylylene diisocyanate

[0218] NMP=n-Methyl pyrolidone

[0219] TEA=triethylamine

[0220] TEOA=triethanolamine

[0221] TETA=triethylenetetramine

[0222] THF=tetrahydrofuran

[0223] Tetraglyme=Tetraethylene glycol dimethyl ether

[0224] Unless otherwise noted, the above chemicals were obtained from
Aldrich (Milwaukee, Wis.) or other similar suppliers of laboratory
chemicals.

[0227] The extent of polyurethane reaction was determined by detecting NCO
% by dibutylamine titration, a common method in urethane chemistry.

[0228] In this method, a sample of the NCO containing prepolymer is
reacted with a known amount of dibutylamine solution and the residual
amine is back titrated with HCl.

Particle Size Measurements

[0229] The particle size for the polyurethane dispersions, pigments and
the inks were determined by dynamic light scattering using a
Microtrac® UPA 150 analyzer from Honeywell/Microtrac (Montgomeryville
Pa.).

[0230] This technique is based on the relationship between the velocity
distribution of the particles and the particle size. Laser generated
light is scattered from each particle and is Doppler shifted by the
particle Brownian motion. The frequency difference between the shifted
light and the unshifted light is amplified, digitalized and analyzed to
recover the particle size distribution.

[0231] The reported numbers below are the volume average particle size.

Solid Content Measurement

[0232] Solid content for the solvent free polyurethane dispersions was
measured with a moisture analyzer, model MA50 from Sartorius. For
polyurethane dispersions containing high boiling solvent, such as NMP,
tetraethylene glycol dimethyl ether, the solid content was then
determined by the weight differences before and after baking in
150° C. oven for 180 minutes.

MW characterization

[0233] All molecular weights were determined by GPC (gel permeation
chromatography) using poly(methyl methacrylate) standards with
tetrahydrofuran as the elutent. Using statics derived by Flory, the
molecular weight of the polyurethane may be calculated or predicted based
on the NCO/OH ratio and the molecular weight of the monomers

Urea Terminated Polyurethane Dispersant Example 1 IPDI/T650/DMPA AN45

[0234] A 2 L reactor was loaded with 136.7 g Terathane® 650, 84.3 g
tetraethylene glycol dimethyl ether, and 32.1 g dimethylol proprionic
acid. The mixture was heated to 110° C. with N2 purge for 1
hr. Then the reaction was cooled to 80° C., and 0.3 g dibutyl tin
dilaurate was added. Over 30 minutes 108.9 g isophorone diisocyanate was
added followed by 28.2 g tetraethylene glycol dimethyl ether. The
reaction was held at 80° C. for 5.5 hrs when the % NCO was below
1.6%. Then, 11.9 g bis(2-methoxy ethyl)amine was added over 5 minutes.
After 2 hr at 80° C., the polyurethane solution was inverted under
high speed mixing by adding a mixture of 45% KOH (22.8 g) and 320 g water
followed by an additional 361.5 g water. The polyurethane dispersion had
a viscosity of 20.6 cPs, 23.7% solids, particle size of d50=14 nm and
d95=18 nm, and molecular weight by GPC of Mn 6320, Mw 17000, and Pd 2.7.
The urea content is 4.1%.

Urea Terminated Polyurethane Dispersant Example 2 IPDI/T650/DMPA AN30

[0235] A 2 L reactor was loaded with 154.3 g Terathane® 650, 95.2 g
tetraethylene glycol dimethyl ether, and 20.4 g dimethylol proprionic
acid. The mixture was heated to 110° C. with N2 purge for 10
min. Then the reaction was cooled to 80° C., and 0.4 g dibutyl tin
dilaurate was added. Over 30 minutes 96.0 g isophorone diisocyanate was
added followed by 24.0 g tetraethylene glycol dimethyl ether. The
reaction was held at 80° C. for 2 hrs when the % NCO was below
1.2%. Then, 10.6 g bis(2-methoxy ethyl)amine was added over 5 minutes.
After 2 hr at 80° C., the polyurethane solution was inverted under
high speed mixing by adding a mixture of 45% KOH (16.8 g) and 236 g water
followed by an additional 467 g water. The polyurethane dispersion had a
viscosity of 11.4 cPs, 25.3% solids, particle size of d50=22 nm and
d95=35 nm, and molecular weight by GPC of Mn 6520, Mw 16000, and Pd 2.5.
The urea content is 8.8%.

[0236] A 2 L was loaded reactor with 245.4 g PO3G (1075 MW) and heated to
110° C. under vacuum until contents had less than 600 ppm water.
Then, added 170 g tetraethylene glycol dimethyl ether, and 22.4 g
dimethylol proprionic acid. The reactor was cooled to 60° C., and
0.36 g dibutyl tin dilaurate was added. Over 1 hour, 96.7 g isophorone
diisocyanate was feed in followed by 21.5 g tetraethylene glycol dimethyl
ether. The reaction was held at 80° C. for 2 hrs when the % NCO
was below 0.9%. The reaction was cooled to 50° C., and then, 35.3
g of 30 wt. % bis(methoxyethyl)amine in water was added over 5 minutes.
After 0.5 hr at 60° C., the polyurethane solution was inverted
under high speed mixing by adding a mixture of 45% KOH (18.8 g) and 262.5
g water followed by an additional 631.6 g water. The polyurethane
dispersion had a viscosity of 13 cPs, 25.5% solids, and particle size of
d50=35 nm and d95=47 nm. The urea content is 2.8%.

[0237] A 2 L was loaded reactor with 214.0 g PO3G (545 MW), 149.5 g
tetraethylene glycol dimethyl ether, and 18.0 g dimethylol proprionic
acid. The mixture was heated to 110° C. under vacuum until
contents had less than 500 ppm water. Then the reaction was cooled to 50
C, and 0.24 g dibutyl tin dilaurate was added. Over 30 minutes 128.9 g
isophorone diisocyanate was added followed by 21.2 g tetraethylene glycol
dimethyl ether. The reaction was held at 80 C for 3 hrs when the % NCO
was below 1.1%. The reaction was cooled to 50° C., and then, 14.1
g bis(2-methoxy ethyl)amine was added over 5 minutes. After 1 hr at
60° C., the polyurethane solution was inverted under high speed
mixing by adding a mixture of 45% KOH (15.1 g) and 211.2 g water followed
by an additional 727.8 g water. The polyurethane dispersion had a
viscosity of 7.86 cPs, 25.5% solids, and particle size of d50=47 nm and
d95=72 nm. The urea content is 3.8%.

[0238] A 2 L was loaded reactor with 166.4 g PO3G (545 MW), 95.8 g
tetraethylene glycol dimethyl ether, and 21.2 g dimethylol proprionic
acid. The mixture was heated to 110° C. under vacuum until
contents had less than 400 ppm water; approximately 3.5 hrs. Then the
reaction was cooled to 70 C, and over 30 minutes, 89.7 g Toluene
diisocyanate was added followed by 15.8 g tetraethylene glycol dimethyl
ether. The reaction was held at 80° C. for 2 hrs when the % NCO
was below 1.5%. Then, 12.4 g bis(2-methoxy ethyl)amine was added over 5
minutes. After 1 hr, removed 50 g for analysis. The remaining
polyurethane solution was inverted under high speed mixing by adding a
mixture of 45% KOH (15.5 g) and 218.0 g water followed by an additional
464 g water.

[0239] The polyurethane dispersion had a viscosity of 17.6 cPs, 22.9%
solids, particle size of d50=16 nm and d95=35 nm, and molecular weight by
GPC of Mn 7465, Mw 15500, and Pd 2.08. The urea content is 4.3%.

[0240] The preparation was identical to Dispersant Example 5 except
methylene diphenyl diisocyanate was used instead of toluene diisocyanate
and the formulation was adjusted for molecular weight differences in
order to maintain the same NCO/OH ratio. The polyurethane dispersion had
a viscosity of 23.5% solids, 34 cPs, particle size of d50=18 nm and
d95=23 nm, and molecular weight by GPC of Mn 11692, Mw 29141, and Pd
2.49. The urea content is 3.7%.

[0241] The preparation was identical to Dispersant Example 5 except
isophorone diisocyanate was used instead of toluene diisocyanate and the
formulation was adjusted for molecular weight differences in order to
maintain the same NCO/OH ratio. The polyurethane dispersion had a
viscosity of 24.4% solids, 22.1 cPs, particle size of d50=nm and d95=nm,
and molecular weight by GPC of Mn 8170, Mw 18084, and Pd 2.21. The urea
content is 4.2%.

[0242] A 2 L reactor was loaded with 194.3 g PO3G (1516 MW), 95.8 g
tetraethylene glycol dimethyl ether, and 21.0 g dimethylol proprionic
acid. The mixture was heated to 110° C. under vacuum until
contents had less than 400 ppm water; approximately 3.5 hrs. Then the
reaction was cooled to 70 C, and over 30 minutes, 69.6 g m-isophorone
diisocyanate was added followed by 11.6 g tetraethylene glycol dimethyl
ether. The reaction was held at 80° C. for 4.5 hrs when the % NCO
was below 1.1%. Then, 7.6 g bis(2-methoxy ethyl)amine was added over 5
minutes. After 1 hr, removed 50 g for analysis. The remaining
polyurethane solution was inverted under high speed mixing by adding a
mixture of 45% KOH (15.4 g) and 216 g water followed by an additional 478
g water. The polyurethane dispersion had a viscosity of 8.8 cPs, 23.2%
solids, particle size of d50=12 nm and d95=23 nm, and molecular weight by
GPC of Mn 8848, Mw 19048, and Pd 2.15. The urea content is 2.6%.

[0243] A 2 L reactor was loaded with 221.6 g Terathane 1000 (977 MW),
127.5 g tetraethylene glycol dimethyl ether, and 27.0 g dimethylol
proprionic acid. The mixture was heated to 110° C. under vacuum
for 1 hour. Then the reaction was cooled to 90° C., and 0.32 g
dibutyl tin dilaurate was added. Over 30 minutes 115 g m-Tetramethylene
xylylene diisocyanate was added followed by 18.9 g tetraethylene glycol
dimethyl ether. The reaction was held at 90° C. for 2 hrs when the
% NCO was below 0.7%. Then, 11.4 g bis(2-methoxy ethyl)amine was added
over 5 minutes. After 1 hr, the polyurethane solution was inverted under
high speed mixing by adding a mixture of 45% KOH (22.6 g) and 316 g water
followed by an additional 640 g water. The polyurethane dispersion was
25% solids with mean particle size of d50=34 nm and d95=48 nm. The urea
content is 3.0%.

[0244] The preparation was identical to Dispersant Example 1 with
additional dimethylol proprionic acid replacing some of the Terathane 650
to adjust the final acid number of the polyurethane to 60 mg KOH/g
polymer while maintaining the same NCO/OH ratio. This polyurethane
dispersion had a viscosity of 21 cPs at 24.1% solids, particle size of
d50=19 nm and d95=24 nm, and molecular weight by GPC of Mn 5944.

[0246] A 2 L reactor was loaded with 214.0 g polytrimethylene ether glycol
(Mn of 545), 149.5 g tetraethylene glycol dimethyl ether, and 18.0 g
dimethylol proprionic acid. The mixture was heated to 110° C.
under vacuum until contents had less than 500 ppm water. The reactor was
cooled to 50° C., and 0.24 g dibutyl tin dilaurate was added.
128.9 g isophorone diisocyanate was added over thirty minutes, followed
by 21.2 g tetraethylene glycol dimethyl ether. The reaction was held at
80° C. for 3 hrs, and the wt % NCO was determined to be below
1.1%. The reaction was cooled to 50° C., then 14.1 g
bis(2-methoxyethyl) amine was added over 5 minutes. After 1 hr at
60° C., the polyurethane solution was inverted under high speed
mixing by adding a mixture of 45% KOH (15.1 g) and 211.2 g water,
followed by an additional 727.8 g water.

[0247] The resulting polyurethane had an acid number of 20 mg KOH/g
solids, and the polyurethane dispersion had a viscosity of 7.86 cPs, 25.5
wt % solids, and a particle size of d50=47 nm and d95=72 nm. The urea
content is 3.8%.

[0248] This polyether diol was prepared in a manner similar to Example 1
with less dimethylol proprionic acid and Terathane 250 instead of
Terathane 650 to adjust the final acid number of the polyurethane to 40
mg

[0249] KOH/g polymer while maintaining the same NCO/OH ratio. The
polyurethane solution was neutralized with TEA and inverted in water.
This polyurethane dispersion had a viscosity of 25.1 cPs at 21.1% solids,
particle size of d50=6.4 nm and d95=8.2 nm, and molecular weight by GPC
of Mn 4301.

[0250] A 2 L reactor was loaded with 154.7 Terathane 650, 95.3 g
tetraethylene glycol dimethyl ether, and 20.3 g dimethylol proprionic
acid. The mixture was heated to 110° C. with N2 purge for 10 min.
Then the reaction was cooled to 80° C. Over 30 minutes 96.1 g
isophorone diisocyanate was added followed by 24.0 g tetraethylene glycol
dimethyl ether. The reaction was held at 85° C. for 3 hrs when the
% NCO was below 1.2%. Then, 10.3 g dibutyl amine was added over 5
minutes. After 1 hr at 85° C., the polyurethane solution was
inverted under high speed mixing by adding a mixture of 45% KOH (16.8 g)
and 244 g water followed by an additional 458 g water. The polyurethane
dispersion had a viscosity of 13.1 cPs, 25.3% solids, and particle size
of d50=19 nm and d95=30 nm.

[0251] To a dry, alkali- and acid-free flask, equipped with an addition
funnel, a condenser, stirrer and a nitrogen gas line was added 55 g 1,6
Hexanediol, 48 g DMPA, 32.2 g TEA, 100 g acetone and 0.06 g DBTL. The
contents were heated to 40° C. and mixed well. 227 g IPDI was then
added to the flask via the addition funnel at 40° C. over 60 min,
with any residual IPDI being rinsed from the addition funnel into the
flask with 10 g acetone.

[0252] The flask temperature was raised to 50° C., held at
50° C. until NCO % was 3.5%% or less, then 39.5 gram DEA was added
over 5 minutes followed by 5 gram acetone rinse. After 1 hour at
50° C., 613 g deionized (DI) water was added over 10 minutes via
the addition funnel. The mixture was held at 50° C. for 1 hr, then
cooled to room temperature.

[0253] Acetone (-115 g) was removed under vacuum, leaving a polyurethane
solution with about 35.0% solids by weight. The final polyurethane
dispersion had a viscosity of 30 cPs, pH 7.5, particle size of d50=86.5
nm.

[0254] To a dry, alkali- and acid-free flask, equipped with an addition
funnel, a condenser, stirrer and a nitrogen gas line was added 125 g
Terathane650, a 650 MW polyether diol from Invista, 25 g DMBA, and 0.04 g
DBTL. The contents were heated to 90° C. and mixed well. 110 g
TMXDI was then added to the flask via the addition funnel at 90°
C. over 60 min. The flask temperature was raised to 95° C., held
at 95° C. until NCO % was 2.9% or less, then 17.8 gram DEA was
added over 5 minutes. After 1 hour at 95° C., the flask
temperature was lowered to 75° C. 15.4 gram TEA was then added
followed by 465 g deionized (DI) water over 10 minutes via the addition
funnel. The mixture was held at 75° C. for 1 hr, then cooled to
room temperature.

[0255] The final polyurethane dispersion had a viscosity of 40 cPs, 37.6%
solids, pH 7.9, particle size of d50=14.5 nm.

[0256] To a dry, alkali- and acid-free flask, equipped with an addition
funnel, a condenser, stirrer and a nitrogen gas line was added 155 g
Terathane650, a 650 MW polyether diol from Invista, 18 g DMBA, and 0.04 g
DBTL. The contents were heated to 90° C. and mixed well. 110 g
TMXDI was then added to the flask via the addition funnel at 90°
C. over 60 min. The flask temperature was raised to 95° C., held
at 95° C. for 1 hour, then 8 gram DEA was added over 5 minutes and
held at 95° C. until NCO % was 1.5% or lower. The flask
temperature was lowered to 75° C. 11.55 TEA was added and mixed
well. 325 g deionized (DI) water was added over 10 minutes via the
addition funnel followed by mixture of 6-aminocaproic acid (13.6 g), TEA
(9.4 g) and water (130 g) solution. The dispersion was held at 75°
C. for 1 hr, then cooled to room temperature.

[0257] The final polyurethane dispersion had a viscosity of 40 cPs, 28%
solids, pH 10, particle size of d50=18.5 nm.

[0258] To a dry, alkali- and acid-free flask, equipped with an addition
funnel, a condenser, stirrer and a nitrogen gas line was added 115 g
Terathane 650, a 650 MW polyether diol from Invista, 39 g DMPA and 115 g
Tetraglyme. The contents were heated to 60° C. and mixed well. 115
g IPDI was then added to the flask via the addition funnel at 60°
C. over 60 min, with any residual IPDI being rinsed from the addition
funnel into the flask with 10 g Tetraglyme.

[0259] The flask temperature was raised to 80° C., held for 120
minutes until NCO % was 1.17% or less, then 10.5 gram DEA was added over
5 minutes.

[0260] With the temperature at 80° C., mixture of 34.4 gram 45% KOH
solution and 754.5 g deionized (DI) water was added over 10 minutes via
the addition funnel. The mixture was held at 50° C. for 1 hr, then
cooled to room temperature. The final polyurethane dispersion had a
viscosity of 18.5 cPs, 24% solids, pH 7.42, particle size of d50=4.4 nm.

[0261] To a dry, alkali- and acid-free flask, equipped with an addition
funnel, a condenser, stirrer and a nitrogen gas line was added 140 g
Terathane 650, a 650 MW polyether diol from Invista, 47 g DMPA, 33.3 g
TEA, 100 g acetone and 0.06 g DBTL. The contents were heated to
40° C. and mixed well. 140 g IPDI was then added to the flask via
the addition funnel at 40° C. over 60 min, with any residual IPDI
being rinsed from the addition funnel into the flask with 10 g acetone.

[0262] The flask temperature was raised to 50° C., held at
50° C. until NCO % was 1.15% or less, then 12.9 gram DEA was added
over 5 minutes followed by 5 gram acetone rinse. After 1 hour at
50° C., 633 g deionized (DI) water was added over 10 minutes via
the addition funnel. The mixture was held at 50° C. for 1 hr, then
cooled to room temperature.

[0263] Acetone (-115 g) was removed under vacuum, leaving a polyurethane
solution with about 35.0% solids by weight. The final polyurethane
dispersion had a viscosity of 500 cPs, pH 7.6, particle size of d50=9.3
nm.

[0264] To a dry, alkali- and acid-free flask, equipped with an addition
funnel, a condenser, stirrer and a nitrogen gas line was added 140 g
Terathane 650, a 650 MW polyether diol from Invista, 44 g DMPA, 31.2 g
TEA, 94 g acetone and 0.06 g DBTL. The contents were heated to 40°
C. and mixed well. 127 g IPDI was then added to the flask via the
addition funnel at 40° C. over 60 min, with any residual IPDI
being rinsed from the addition funnel into the flask with 10 g acetone.

[0265] The flask temperature was raised to 50° C., held at
50° C. until NCO % was 0.53% or less, then 5.6 gram DEA was added
over 5 minutes followed by 5 gram acetone rinse. After 1 hour at
50° C., 578 g deionized (DI) water was added over 10 minutes via
the addition funnel. The mixture was held at 50° C. for 1 hr, then
cooled to room temperature.

[0266] Acetone (-109 g) was removed under vacuum, leaving a polyurethane
solution with about 35.0% solids by weight. The final polyurethane
dispersion had a viscosity of 500 cPs, pH 7.7, particle size of d50=16
nm.

Urea Terminated Polyurethane Dispersant Example 20 IPDI/HD BMEA AN30

[0267] A 2 L reactor was loaded with 70.9 1,6-hexane diol, 55.3 g
tetraethylene glycol dimethyl ether, and 21.5 g dimethylol proprionic
acid. The mixture was heated to 110° C. with N2 purge for 30
min. Then the reaction was cooled to 80° C., and 0.5 g dibutyl tin
dilaurate was added. Over 30 minutes 185.8 g isophorone diisocyanate was
added followed by 45.8 g tetraethylene glycol dimethyl ether. The
reaction was held at 85° C. for 2 hrs when the % NCO was below
2.1%. Then, 20.3 g bis(2-methoxy ethyl)amine was added over 5 minutes.
After 1 hr at 85° C., the polyurethane solution was inverted under
high speed mixing by adding a mixture of 45% KOH (15.7 g) and 222 g water
followed by an additional 489 g water. The polyurethane dispersion had a
viscosity of 9.9 cPs, 25.3% solids, pH 8.0, particle size of d50=17 nm
and d95=26 nm, and molecular weight by GPC of Mn 5611, Mw 10316, and PD
1.8.

Urea Terminated Polyurethane Dispersant Example 21 IPDI/DDD BMEA AN30

[0268] A 2 L reactor was loaded with 95.9 1,12-dodecane diol, 74.9 g
tetraethylene glycol dimethyl ether, and 20.6 g dimethylol proprionic
acid. The mixture was heated to 110° C. with N2 purge for 1
hr. Then the reaction was cooled to 80° C., and 0.4 g dibutyl tin
dilaurate was added. Over 30 minutes 153.5 g isophorone diisocyanate was
added followed by 37.9 g tetraethylene glycol dimethyl ether. The
reaction was held at 85° C. for 2 hrs when the % NCO was below
1.8%. Then, 16.9 g bis(2-methoxy ethyl)amine was added over 5 minutes.
After 1 hr at 85° C., the polyurethane solution was inverted under
high speed mixing by adding a mixture of 45% KOH (16.9 g) and 214 g water
followed by an additional 458 g water. The polyurethane dispersion had a
viscosity of 11.2 cPs, 25.4% solids, pH 7.9, particle size of d50=17 nm
and d95=25 nm, and molecular weight by GPC of Mn 6640, Mw 12615, and PD
1.9.

[0269] The preparation was identical to Dispersant Example 1 with
additional dimethylol proprionic acid replacing some of the Terathane 650
to adjust the final acid number of the polyurethane to 90 mg KOH/g
polymer while maintaining the same NCO/OH ratio. This polyurethane
dispersion had a viscosity of 45.6 cPs at 26.2% solids, particle size of
d50=19 nm and d95=22 nm, and molecular weight by GPC of Mn 6916.

[0270] A 2 L reactor was loaded with 136.5 Terathane 650, 95.5 g
tetraethylene glycol dimethyl ether, and 30.2 g dimethylol proprionic
acid. The mixture was heated to 115° C. with N2 purge for 60
min. Then the reaction was cooled to 80° C. Over 30 minutes 101.3
g trimethylhexamethylene diisocyanate (Vestanat TMDI) was added followed
by 26.0 g tetraethylene glycol dimethyl ether. The reaction was held at
85° C. for 1.5 hrs when the % NCO was below 1.0%. Then, 11.8 g
bis(2-methoxy ethyl)amine was added over 5 minutes. After 1 hr at
85° C., the polyurethane solution was inverted under high speed
mixing by adding a mixture of 45% KOH (25 g) and 349 g water followed by
an additional 349 g water. The polyurethane dispersion had a viscosity of
20.3 cPs, 25.2% solids, and particle size of d50=16 nm and d95=20 nm.

[0271] A 2 L reactor was loaded with 155.0 Terathane 650, 101.9 g
tetraethylene glycol dimethyl ether, and 19.9 g dimethylol proprionic
acid. The mixture was heated to 115° C. with N2 purge for 30
min. Then the reaction was cooled to 80° C. Over 30 minutes 90.3 g
trimethylhexamethylene diisocyanate (Vestanat TMDI) was added followed by
22.3 g tetraethylene glycol dimethyl ether. The reaction was held at
85° C. for 5.5 hrs when the % NCO was below 1.0%. Then, 10.5 g
bis(2-methoxy ethyl)amine was added over 5 minutes. After 1 hr at
85° C., the polyurethane solution was inverted under high speed
mixing by adding a mixture of 45% KOH (16.3 g) and 229 g water followed
by an additional 448 g water. The polyurethane dispersion had a viscosity
of 38.7 cPs, 25.0% solids, and particle size of d50=11 nm and d95=19 nm.

[0272] A 2 L reactor was loaded with 166.4 PO3G (545 MW, 95.8 g
tetraethylene glycol dimethyl ether, and 21.2 g dimethylol proprionic
acid. The mixture was heated to 110° C. under vacuum until
contents had less than 400 ppm water; approximately 3.5 hrs. Then the
reaction was cooled to 70 C, and over 30 minutes, 89.7 g Toluene
diisocyanate was added followed by 15.8 g tetraethylene glycol dimethyl
ether. The reaction was held at 80° C. for 2 hrs when the % NCO
was below 1.5%. Then, 12.4 g bis(2-methoxy ethyl)amine was added over 5
minutes. After 1 hr at 60° C., removed 50 g for analysis. The
remaining polyurethane solution was inverted under high speed mixing by
adding a mixture of 45% KOH (15.5 g) and 218.0 g water followed by an
additional 464 g water. The polyurethane dispersion had a viscosity of
17.6 cPs, 22.9% solids, particle size of d50=16 nm and d95=35 nm, and
molecular weight by GPC of Mn 7465, Mw 15500, and Pd 2.08.

[0273] A 2 L reactor was loaded with 109.7 g Terathane® 650, 33.8 g
tetraethylene glycol dimethyl ether, 6.6 g Dantocol DHE
(1,3-dihydroxyethyl dimethyl hydantoin) and 27.0 g dimethylol proprionic
acid. The mixture was heated to 75° C. with N2 purge for 20
minutes. Then, 0.4 g dibutyl tin dilaurate was added. Over 60 minutes
96.6 g isophorone diisocyanate was added followed by 8.0 g tetraethylene
glycol dimethyl ether. The reaction was held at 80° C. for 4 hrs
when the corrected % NCO was below 1.5%. Then, 9.7 g bis(2-methoxy
ethyl)amine was added over 5 minutes. After 1 hr at 80° C., the
polyurethane solution was inverted under high speed mixing by adding a
mixture of 45% KOH (22.6 g) and 317 g water followed by an additional 372
g water. The polyurethane dispersion had a viscosity of 35 cPs, 25.4%
solids, and a particle size of d50=22.5 nm and d95=26.6 nm. The urea
content is 3.9%.

Comparative Polyurethane Dispersant 1 Diamine as Chain Extender

[0274] To a dry, alkali- and acid-free flask, equipped with an addition
funnel, a condenser, stirrer and a nitrogen gas line was added 699.2 g
Desmophen C 1200, a polyester carbonate diol, (Bayer), 280.0 g acetone
and 0.06 g DBTL. The contents were heated to 40° C. and mixed
well. 189.14 g IPDI was then added to the flask via the addition funnel
at 40° C. over 60 min, with any residual IPDI being rinsed from
the addition funnel into the flask with 15.5 g acetone.

[0275] The flask temperature was raised to 50° C., held for 30
minutes then followed by 44.57 g DMPA, then followed by 25.2 g TEA, was
added to the flask via the addition funnel, which was then rinsed with
15.5 g acetone. The flask temperature was then raised again to 50°
C. and held at 50° C. until NCO % was 1.14% or less.

[0276] With the temperature at 50° C., 1520.0 g deionized (DI)
water was added over 10 minutes, followed by 131.00 g EDA (as a 6.25%
solution in water) over 5 minutes, via the addition funnel, which was
then rinsed with 80.0 g water. The mixture was held at 50° C. for
1 hr, then cooled to room temperature.

[0277] Acetone (-310.0 g) was removed under vacuum, leaving a final
dispersion of polyurethane with about 35.0% solids by weight.

Comparative Polyurethane Dispersant 2 IPDI/PPG400 BMEA AN30

[0278] A 2 L reactor was loaded with 141.5 g Polypropylene glycol 400 MW
(Poly-G 20-265, OH #268, from Arch Chemical), 81.5 g tetraethylene glycol
dimethyl ether, and 21.5 g dimethylol proprionic acid. The mixture was
heated to 110° C. with N2 purge for 1 hr. Then the reaction
was cooled to 70° C., and 0.3 g dibutyl tin dilaurate was added.
Over 30 minutes 121.9 g isophorone diisocyanate was added followed by
20.1 g tetraethylene glycol dimethyl ether. The reaction was held at
80° C. for 5 hrs when the % NCO was below 1.3%. Then, 13.3 g
bis(2-methoxy ethyl)amine was added over 5 minutes. After 2 hr at
80° C., the polyurethane solution was inverted under high speed
mixing by adding a mixture of 45% KOH (15.8 g) and 239 g water followed
by an additional 476 g water. The polyurethane dispersion had a viscosity
of 25.5 cPs, 23.6% solids, pH 8.3, particle size of d50=8 nm and d95=13
nm, and molecular weight by GPC of Mn 5881, Mw 12483, and PD 2.1.

Comparative Polyurethane Dispersant 3 IPDI/PPG1000 BMEA AN30

[0279] A 2 L reactor was loaded with 175.6 g Polypropylene glycol 400 MW
(Poly-G 20-112, OH #112.7, from Arch Chemical), 101.2 g tetraethylene
glycol dimethyl ether, and 20.6 g dimethylol proprionic acid. The mixture
was heated to 110° C. with N2 purge for 1 hr. Then the reaction
was cooled to 70° C., and 0.3 g dibutyl tin dilaurate was added.
Over 30 minutes 80.7 g isophorone diisocyanate was added followed by 13.4
g tetraethylene glycol dimethyl ether. The reaction was held at
80° C. for 3.5 hrs when the % NCO was below 1.3%. Then, 8.9 g
bis(2-methoxy ethyl)amine was added over 5 minutes. After 2 hr at
80° C., the polyurethane solution was inverted under high speed
mixing by adding a mixture of 45% KOH (15.1 g) and 220 g water followed
by an additional 448 g water. The polyurethane dispersion had a viscosity
of 9.7 cPs, 24.2% solids, pH 7.5, and particle size of d50=118 nm and
d95=141 nm.

Preparation of Pigmented Dispersions

[0280] The pigmented dispersions used in this invention can be prepared
using any conventional milling process known in the art. Most milling
processes use a two-step process involving a first mixing step followed
by a second grinding step. The first step comprises a mixing of all the
ingredients, that is, pigment, dispersants, liquid carriers, pH adjuster
and any optional additives to provide a blended "premix". Typically all
liquid ingredients are added first, followed by the dispersants and
lastly the pigment. Mixing is generally done in a stirred mixing vessel
and high-speed dispersers, (HSD), are particularly suitable for the
mixing step. A Cowels type blade attached to the HSD and operated at 500
rpm to 4000 rpm, and preferably 2000 rpm to 3500 rpm, provides optimal
shear to achieve desired mixing. Adequate mixing is achieved usually in
mixing from 15 minutes to 60 minutes.

[0281] The second step comprises grinding of the premix to produce a
pigmented dispersion. Preferably, grinding occurs by a media milling
process although other milling techniques can be used. In this invention
a lab-scale Eiger Minimill, model M250, VSE EXP from Eiger Machinery Inc.
Chicago, Ill. was used. Grinding was accomplished by charging about 820
grams of 0.5 YTZ zirconia media to the mill. The mill disk speed was
operated between 2000 rpm and 4000 rpm and preferably at 3000 rpm and
3500 rpm. The dispersion is processed using a re-circulation grinding
process and flow rates though the mill were typically 200 to 500
grams/min. and preferably 300 grams per min. The milling may be done
using a staged procedure in which a fraction of the solvent is held out
of the grind and added after milling is completed. This amount of solvent
held out during milling varies by dispersion and is typically 200 to 400
grams of the total 800-gram batch size. This is done to achieve optimal
rheology for grinding efficiency. The invention example dispersions each
were normally processed for a total of 4 hours milling time.

[0282] After completion of milling process, the dispersion was filled into
a polyethylene container. Optionally, the dispersion may be further
processed using conventional filtration procedures known in the art. The
dispersions may be processed using ultrafiltration techniques that remove
co-solvents and other contaminants, ions or impurities from the
dispersion. The dispersions were tested for pH, conductivity, viscosity
and particle size. To assess dispersion stability, the above properties
were remeasured after oven aging of samples for 1 week at 70° C.
and noting if significant change versus initial readings had occurred.

[0284] The following procedure was used to prepare the pigment dispersions
with invention dispersing resin. Using an Eiger Minimill, the premix was
prepared at typically 20-30% pigment loading and the targeted dispersant
level was selected at a P/D (pigment/dispersant) ratio of 1.5-3.0.
Optionally, a co-solvent was added at 10% of the total dispersion
formulation to facilitate pigment wetting and at least partial
dissolution of the polyurethanes in premix stage and ease of grinding
during milling stage. Although other similar co-solvents are suitable,
triethylene glycol monobutyl ether (TEB as supplied from Dow Chemical)
was the co-solvent of choice. The invention resins were pre-neutralized
with either KOH or amine to facilitate solubility and dissolution into
water. During the premix stage the pigment level was maintained at
typically 27% and was subsequently reduced to about 24% during the
milling stage by adding deionized water for optimal media mill grinding
conditions. After completion of the milling stage, which was typically 4
hours, the remaining letdown of de-ionized water was added and thoroughly
mixed.

[0285] All the pigmented dispersions processed with co-solvent were
purified using an ultrafiltration process to remove co-solvent(s) and
filter out other impurities and ions that may be present. After
completion, the pigment levels in the dispersions were reduced to about
10 to 15%. A total of 6 different magenta and 3 black dispersions were
prepared with the invention dispersing resins.

[0287] The initial dispersion properties are tabulated and their one-week
oven stability results are reported in Table 1 and 2, respectively. The
initial particle size, viscosity, and conductivity for these dispersions
were 68-144 nm, 3.1-9.8 cPs, and 0.71-2.1 mS/cm, respectively, with the
pH ranging from 8.1 to 9.9. The particle size for these dispersions was
stable with oven aging with a typical, mean particle size change of 20%
with oven aging, but the viscosity and pH did change significantly.

In addition, a dispersion Comparative Dispersion Magenta-1 was made from
the Comparative Dispersant, a diamine chain extended polyurethane
dispersion. This dispersant failed as a dispersant for the magenta
pigment; it gelled at the premix stage of the dispersion process.

[0288] The inks were prepared with pigmented dispersions made using urea
terminated polyurethane dispersant polymers described above, by
conventional process known to the art. The pigmented dispersions were
processed by routine operations suitable for inkjet ink formulation.

[0289] Typically, in preparing ink, all ingredients except the pigmented
dispersion were first mixed together. After all the other ingredients
were mixed, the pigmented dispersion is added. Common ingredients in ink
formulations useful in pigmented dispersions include one or more
humectants, co-solvent(s), one or more surfactants, a biocide, a pH
adjuster, and de-ionized water.

[0290] The selected Magenta pigmented dispersions from example dispersions
in Table 1 were prepared into Magenta ink formulations in which the
targeted percent pigment in ink jet ink was 4.0%. Water, Polyurethane
binder, Dowanol TPM, 1,2-hexanediol, ethylene glycol, Surfynol 445, and
Proxel GXL were mixed with the prepared pigment dispersions in the
percentages detailed in Table 3. Polyurethane binder is a crosslinked
polyurethane dispersion prepared as PUD EXP1 in US 20050215663 A1,
Dowanol TPM is Tripropylene glycol methyl ether from Dow Chemical, Proxel
GXL is a biocide available from Avecia, Inc. and Surfynol 440 is a
surfactant available from Air Products. The inks were mixed for 4 hours
and then filtered through a 1 micron filtration apparatus, removing any
large agglomerates, aggregates or particulates.

[0292] Jet velocity, drop size and stability are greatly affected by the
surface tension and the viscosity of the ink. Inkjet inks typically have
a surface tension in the range of about 20 dyne/cm to about 60 dyne/cm at
25° C. Viscosity can be as high as 30 cPs at 25° C., but is
typically significantly lower. The inks have physical properties
compatible with a wide range of ejecting conditions, i.e., driving
frequency of the piezo element, or ejection conditions for a thermal
head, for either a drop-on-demand device or a continuous device, and the
shape and size of the nozzle. The inks of this invention should have
excellent storage stability for long periods so as not clog to a
significant extent in an ink jet apparatus. Further, it should not alter
the materials of construction of the ink jet printing device it comes in
contact with, and be essentially odorless and non-toxic.

[0293] Although not restricted to any particular viscosity range or
printhead, the inventive inks are suited to lower viscosity applications
such as those required by higher resolution (higher dpi) printheads that
jet small droplet volumes, e.g. less than about 20 pL. Thus the viscosity
(at 25° C.) of the inventive inks can be less than about 10 cPs,
is preferably less than about 7 cPs, and most advantageously is less than
about 5 cPs.

[0294] Print Properties: Paper Substrate The printing of the test examples
was done in the following manner unless otherwise indicated. The printing
for the inks with dispersions prepared with the urea terminated
polyurethanes was done on an Epson 980 printer (Epson America Inc, Long
Beach, Calif.) using the black printhead which has a nominal resolution
of 360 dots per inch. The printing was done in the software-selected
standard print mode. The optical density and chroma were measured using a
Greytag-Macbeth SpectoEye instrument (Greytag-Macbeth AG, Regensdorf,
Switzerland). The DOI was measured by a Byk Gardner Wave-Scan DOI and the
Gloss was measured by Byk Gardner Micro-TRI-Gloss. (Byk-Gardner,
Columbia, Md.

[0295] Unless otherwise specified the ink formulation was as follows with
all components as weight percent

The inventive inks as pigmented inks rival the OD and DOI the less
durable dye inks.

[0297] Optical Properties of Prints from the Inventive Inks

[0298] Inks were prepared using the formulation shown in Table 5 and the
dispersants noted in Table 7. The optical properties were measured. The

[0299] NCO/OH mole ratio noted is the ratio of NCO/OH of the added
isocyanate and isocyanate reactive components for preparation of the
prepolymer, just prior to the addition of the chain terminated amine.

It synthesis is similar to Example 1c of previously incorporated
US2005/0090599 except 2-ethylhexyl methacrylate was substituted for
benzylmethacrylate. The inventive inks with the urea terminated
polyurethane dispersants produce better Gloss and DOI than similar
pigmented inks with acrylic dispersants.

[0300] Printing Properties: Textiles

[0301] The Inkjet inks with invention dispersing resins were printed using
a commercially available Epson 3000 piezo printhead type printer although
any suitable inkjet printer could be used. The substrate used was 419
100% cotton from Testfabrics. The printed textiles may optionally be post
processed with heat and/or pressure, such as disclosed in US20030160851
(the disclosure of which is incorporated by reference herein for all
purposes as if fully set forth. In this case, all test prints were fused
at about 170° C. for about 2 minutes.

[0303] Where indicated the printed textile was tested for washfastness
according to methods developed by the American Association of Textile
Chemists and Colorists, (AATCC), Research Triangle Park, NC. The AATCC
Test Method 61-1996, "Colorfastness to Laundering, Home and Commercial:
Accelerated", was used. In that test, colorfastness is described as "the
resistance of a material to change in any of its color characteristics,
to transfer of its colorant(s) to adjacent materials or both as a result
of the exposure of the material to any environment that might be
encountered during the processing, testing, storage or use of the
material." Tests 3A was done and the color washfastness and stain rating
were recorded. The ratings for these tests are from 1-5 with 5 being the
best result, that is, little or no loss of color and little or no
transfer of color to another material, respectively. Crock measurements
were made using methodology described in AATCC Test Method 8-1996.

[0304] The printing results using an Epson 3000 piezo type printer, for
selective inks make with pigments stabilized by invention dispersing
resins are reported in Table 5.

[0305] The salt stability test was introduced as a means to measure
polymeric dispersions and their propensity to `crash` out onto a
substrate, especially paper. This was described in previously
incorporated US2005/0090599.

[0317] Dispersions of 5 urea terminated polyurethanes dispersants and two
comparison ionically stabilized dispersants were prepared with a magenta
pigment in a manner similar to what was described above for M1-M5. These
were tested for salt stability which is the test that differentiates
between ionically stabilized dispersants and conventionally dispersed
pigments. Each dispersion was milled for 12 passes at flow rate of 350
ml/min and 15,000 psi through the a labscale model M-110Y High Pressure
Pneumatic Microfluidizer, with a Z-Chamber available from Microfluidics
of Newton, Mass. KOH was used to as neutralization ingredient. Nipex 180
pigment was used at 15 wt %, a 2.5 pigment/dispersant ratio and 8% of TEB
as the water miscible cosolvent. The balance of the dispersion mixture
was deionized water.

All of the Inventive dispersions and the comparative dispersions have the
property that they precipitate when tested with the salt stability.
Dispersant Example 8 has a particularly low salt stability, which is
particularly advantageous when this dispersion would be converted to and
ink for achieving high quality inkjet printed images on a substrate.